All perfect praise be to Allah, the Lord of the Worlds; may His blessings and peace be upon our Prophet Mohammad and upon all his family and companions.
A power of attorney is a non-binding contract between two parties, so you can have it terminated whenever you like. Thus, you can go to court or the notary public and declare that you wish to cancel that power of attorney, then go on with the needed procedures to have that done. However, if this isn`t possible legally, then we recommend that you consult a lawyer. And Allah The Almighty Kmows Best.