Yes, the person (the "principal") who grants a power of attorney (POA) may revoke it at all and/or can appoint someone else to be his attorney-in-fact or agent (those are the terms for the person granted authority by a POA). Your father can draft a new POA for you which also specifically says it revokes and supercedes any earlier POAs. You and your father should let an attorney help you, so as to make sure it is drated and witnessed properly, so as to be effective.