Trying to deauthorize ArcGIS v10.6.1 single use license prior to updating the software to v10.7.1. Deauthorizing software failed error; with this message "Error 7466: The return of this fulfillment is denied by the return policy because max return exceeded."
Software license is current, single use. Windows 10 operating system.
Update: Rename FLEXnet folder to FLEXnet_old in Windows Explorer. Then open ArcGIS Administrator and Authorize Now.