2560 Revocation of Power of Attorney and Withdrawal of Attorney [R-07.2015]
The revocation or withdrawal of an attorney may be submitted at any time; however, a revocation or withdrawal of an attorney filed after issuance of a patent is not normally processed.
It should be noted that an assignment does not act as a revocation of power of attorney for authorization previously given. However, the assignee may revoke a previous power of attorney. See 37 CFR 3.71 and 3.73.