Can my grandparents POA agents be revoked of their titles?

Out for my grandparents 6 children, 2 of them went behind everyone's back and became POA agents for my grandparents. However, my grandparent a very much competent and able to make rational decisions the POAs are doing things without them knowing. a couple main issues: my uncle made them "do not report" status while they're in the hospital so no one can call to see what room they're doing/the status of their health. My aunt recently put her hand on me for no good reason so I defended myself and it end in a fist fight and her in the ER. After that she used her POA title to put a code on my grandmas hospital room so now no one but herself, my uncle and my grandfather can visit. We found this out when my youngest brother who takes care of her when she is home tried visiting and was confronted by security at the door. She begged for them to let him in her room and after speaking with several people he was finally allowed to visit with her. What can we do?