How can I revoke being my dad's POA?

I can't handle the stress. I saw a post on this site from 5 years ago that resonated but I just need to vent. My mother passed away a year ago and since she passed I have spent the last year of my life cleaning up my dad's messes due to his impaired judgement. His bank account was cleaned out by one of my siblings, he was hospitalized, he has a vacant house that is falling apart and doesn't care, and on top of it, just found out he was diagnosed with dementia. I have no support in our family. I have 3 siblings and my dad has multiple siblings, all of which think there is nothing wrong (they aren't around to see), or they are only interested in taking his money. I am not biologically connected to him and did not grow up with him my whole life so our relationship is more business like. I thought at first I could handle this but it's clear my so called family doesn't care and I want to scream when they offer their "suggestions"; all from people who have no clue of what I've been dealing with. I am 34 years old. I am grieving my mom and wanted to go back to school and this is consuming my life. My dad listed one of my siblings as an alternate POA and they don't want it either. My head tells me to get out but my heart says to be compassionate and be there for him. I have been alone my whole life with no family support but this is a major thing to be alone with. I just don't think I can do it. Like I said I just needed to vent.