Unregister a Firepower Management Center
Unregister a Firepower Management Center from the Cisco Smart Software Manager before you reimage the FMC. This also unregisters any managed Firepower Threat Defense devices.
If the FMC is configured for high availability, licensing changes are automatically synchronized. You do not need to unregister the other FMC.
Log into the Firepower Management Center.
Next to Smart License Status, click the stop sign ().
Read the warning and confirm that you want to unregister.