Mom asked us to remove my sister as power of attorney but we have no rights. Advice?

My sister grabbed pow..sense she took all moms property for self and items I.put in moms house such as a portable building my 13 ye old step daughter got killed..with her insurance money we bought it to store her things we couldn't part with..and all in it..also she spends every dime on.self..she gambles and moms bank.stays over.drawn with fees. 900.00 last month..mom lives with her..if I complain I loose my visits and my sister says very mean things to me like my mom didn't like me and I was so close to my momma..my moms house was foreclosed and her car went for report last year..that's the 2nd car sister put for repo..my mom makes very good money ..my Mon lives with her and she keeps her in bed all but from 6 p.m. till 10. My mom wants to go places with her other kids but sister wont let her..I feel so sad and depressed for.my mom..my sister controls her every move and my mom was so kind and such a giver.to all her kids..my sister pays some to a c.n.a however we are all wanting and.skilled to care for mom..she.plays scratch offs into the thousands and moms account is over drawn..she got a dnr and none.of the siblings were asked..she makes me feel powerless as she knows I have no money for attorneys and if I.tell ill never see mom again..I think somehow my mom should have a say..she only has memory loss at my sisters discretion ..shell say momma said so but then on the other hand shell say moms memory is gone..she uses that to best suit her. Most items in mommas house were what I put there and she took them all...there has got to be relief for my mom..my mom.would never approve of how she is treating her kids..my moms asked many times to remove her.from power of attorney but we feel we have no rights..please help my momma..