MPEP 2560
Revocation of Power of Attorney and Withdrawal of Attorney
This is the Ninth Edition of the MPEP, Revision 08.2017, Last Revised in January 2018
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.