The principal, or the person that the medical POA is assigned to, can terminate the arrangement at any time. Of course, if the principal is no longer sound of mind this will be taken into consideration by the court.
People who can override the POA
Other people can potentially override the medical power of attorney arrangement on the principal’s behalf. For instance, if a loved one is concerned that your medical POA is abusing their power or taking advantage of you, they can petition the court.
Keep in mind that the POA, also known as the agent, cannot transfer their responsibilities to another person. They do not have the authority to assign a different POA to you.