Can a principle change her own POA once it’s been activated?

If the POA has been invoked because you have proof of incompetence then nothing she can do. Blaming you because the state revolked her license is unreasonable. Just read that memory is effected in last stage of cirrhosis. Moms continued drinking doesn't help. Maybe she needs a LTC facility where she can't get liquor.

I am wondering how she gets the alcohol? Is someone at the facility buying it for her?
Is there a substance abuse rehab she can go to?
Does she still have a car?
Is it possible for you to remove her car from the facility where she is so she can not drive.
OK got that off my mind.
Can you explain to her that if you are not POA a Guardian may have to be appointed and it will either be you or the State will appoint a Guardian and you will be much easier to deal with than a State appointed guardian.

Ammonia levels affect mental competence; to change POA under those circumstances would require a court-appointed guardian. See an eldercare attorney to get that organized. A better alternative is get her on Medicaid and nursing home, but she will probably need to be hospitalized to be "dried up" from the booze and alcohol withdrawals. Her ammonia levels need to be monitored and her doctor may put her on scheduled lactulose if they are high.

In Illinois, an individual can revoke their POA at any time no matter the level of incompetence and it can be done verbally. For instance, she can tell her doctor or someone at the facility she is in that she no longer wants you to be her POA. POA only works as long as the parent is cooperative. The only way you can legally take responsibility for your mom is to file for plenary guardianship (both for the person and their estate--managing income, paying bills, etc.). You will need an attorney and the court will assign an attorney for her. It's not easy to go through but when a parent becomes uncooperative with decisions that are in their best interest, it's the only way to be sure you can help her. Without guardianship she can sign herself out of any facility you put her in. It will help if her doctor is willing to sign a statement that she is incompetent, which, I've found, doctors are very reluctant to do or even refuse to do despite the obvious. Otherwise, the judge is left to form his own opinion based on evidence provided. We had to do this with my mother-in-law because she refused to leave her home even though she could no longer safely live there even with daily home aides coming in. It was terrible to have to testify in court about what was happening with her sitting there but we all know we did the right thing for her and she didn't remember it had even happened a minute after we left the courthouse. You are in a tough place, one many of us have been or are in now.

Sounds like you have a few things going on here. I believe POA and DPOA are different in the "power" and power to revoke they represent and then you have Gardianship which is another animal and typicaly used when the paitent either doesn't have a DPOA in place or is no longer in their right mind or doing things to harm themselves or others and fighting the appointed person. It get's more confusing of course because there are sometimes slight diffrences based in the State the LO lives in and I don't know anything about your state. However since there is a very good chance a lawer was involved in drawing up the POA and or DPOA that exists, that's where I would start. Get in touch with that attorney and ask them what power it gives you in the event she isn't thinking clearly or being cooperative. A simple POA is just the ability to act as that person wants "on their behalf" so yes if she is in her right mind she can change that. You mention the doctor however told you it was time to invoke the POA which is what makes me wonder if it's actually more than that or if there is a loophole in her state not allowing her in her present state of mind to change it.

On the subject of the battles that are becoming so intense with your mom, first does she have someone else to appoint POA? If so maybe it would be helpful for you, take that pressure and wedge out of your relationship. I suspect not though so my suggestion would be to make her doctor or doctors the heavy as much as you can. If indeed her doctor is wanting you to take the reigns and recognizes her issues maybe he or she will be willing to take the heat. I find with my mom that while she may be disgruntled by something (like loosing driving privledges) she is far less apt to argue or push back whith the doctor and we (her kids and POA's) are just following doctors orders. We remind her all the time it was DR... who insisted or even use it as a subtle threat when she wants to be obstinent with us, that's fine Mom but DR... may just take it out of our hands if this doesn't improve. She knows the doctor can call in "outsiders" and while it's all kind of nebulus about what the can or might do the fear of losing all decision making control for her and us is enough to get her to cooperate most of the time. This way while I am facilitating whatever it is she doesn't really want to do, I'm doing what has to be done to protect her from the unknown. We even do little things sometimes to lighten up the restrictions, for instance she isn't supposed to have any salt but it's impossible with her so I'll say have some peanut butter on those crackers (she likes to just lick the salt off an entire package or two at a time) so you get some nourishment and it might help you eat fewer, instead of reprimanding her for the crackers at all. Oh and now I tell her ok if you are going to eat salty foods on a given day so be it but you need to drink extra water on those days you do so your decision, extra water so you can have ham and cheese on crackers (Ugh!) or forget the salty foods so you don't need extra water. Just an example but that all then plays into her bloodwork results and she knows that particularly when we remind her, no hiding results from the doctor...brings us back to using them as the heavy. It's not perfect and don't have the added challenge of alcohol but for us anyway so far it's helped maintain our relationship with her as well as our ability to manage/care for her.

You need to get guardianship, that allows you to make decisions for her , sounds like she is no longer able to make them for herself, probably should talk to a good elder lawyer

It depends on what your Mother's Power of Attorney document states. 

My parents' Durable Power of Attorney documents went into effect as soon as they signed them and they did not mention the ability to change the POA once the POA was invoked.  Also, their POA document DID NOT require a doctor to declare them as "incompetent" in order for the POA to be invoked because they owned farms and someone needed to be able to take care of the farm finances and other farm related business whenever they could not. I did not need to "invoke" Dad's POA as he was still able to handle his farm's business up until the day he died. I did have to "invoke" Mom's POA and "take over" her farm business because she could not figure out what needed to be paid when or how to write a check, etc.

You need to read your Mother's POA document and/or ask your attorney what the POA allows or does not allow your Mother to do once the POA is invoked.

Also, has your Mom been evaluated by a geriatric psychiatrist or a psychiatric nurse practitioner? If not, then she needs to be. The geriatric psychiatrist or a psychiatric nurse practitioner can evaluate your Mom’s thought process, sensorium (alert and oriented X 3), cognitive function, knowledge base, abstract thought, memory, judgment, insight and calculation ability.  

My Mom was evaluated by the facility's psychiatric nurse practitioner.  Mom “passed” the MINI-MENTAL EXAM and was “Alert and Oriented X 3”, but she had “Ideas of Unreality – delusional statements”; her thought process was “Confused, derails often with periods of lucidity” and her cognitive function, knowledge base, abstract thought, memory, judgment, and insight were all “impaired" and she could not figure out how many quarters were in $2.75.  Unfortunately the Social Service Assistant at the nursing home thought that Mom was competent and able to take care of her own finances. So when Mom became angry at me and my brother for making arrangements to pay for Mom's nursing home bill while we waited for Mom's Long Term Care Insurance to go into effect, the Social Service Assistant "helped" Mom to revoke my brother and myself as POAs and name our family attorney as POA.  I had to hire my own attorney and petition for guardianship and conservatorship.  During the process, the Attorney Ad Lidem assigned by the Court to represent Mom decided that Mom DID NOT know what she was doing nor understand the consequences and asked the Court to "disregard" the revocation that Mom had made and return Power of Attorney to me.  If the Social Service Assistant had read psychiatric nurse practitioner's notes, maybe she would not have encouraged Mom to revoke my POA.  Who knows!?!

Having an psychiatric evaluation available in your Mom’s health records that proves that your Mom is NOT able to handle her own affairs will strengthen your position as her POA—especially if your Mom (or someone well-meaning person thinks that your Mom is competent) challenges your POA status.

Llama they can indeed get a drinky poo in AL. I worked at a place that was Il through NH, and they had wine with dinner if they wanted it. AL assumes they need some help, but can still make some decisions on their own. My mom was in rehab for CHF and pneumonia, and her Dr wrote her a "script" for a glass of wine a night. (ok;ed by her cardiologist) They sure don't advertise these places as prisons, instead of lifestyle places. But I think if she has been kicked out by several places she needs more than AL. If they can get out and buy their own stuff ( food, cigs, etc) then they can't stop them from "free will". It is not good but it is what it is.

I believe that in Wisconsin two doctors have to agree she is not competent to make her own decisions. After that she will have no way to revoke your POA. My mother occasionally threatens to take mine away but then forgets about it the next day. It is a hard place to be in.

If she has been declared incompetent by one or two doctors (depending on what it says is her POA), she can not take you off as POA. If she was never declared incompetent by the doctor she can change her POA at any time.

Dealing with seniors who should not be driving.
There are many ways to try to address this but here is what I have found. Most families don't want to be the one to tell a parent that they can not drive because it can cause a lot of problems in their relationship with the parent. What I have my families do is call the Department of Revenue and tell them that individual is unsafe to be driving. The Department of Revenue will then contact the individual and tell them that they are going to have to submit to a driving test to keep their license. If the senior truly is not safe to drive they will not pass the test.

Another thing I have done is have the seniors doctor write a doctor's order to the individual telling them that they can no longer drive. Some seniors will follow any order their doctor tells them. Sounds simple but has worked with some seniors.