This article explains the steps involved in unregistering the Site Recovery Manager Appliance and vSphere Replication Appliance.
VMware vCenter Server 7.x
VMware vCenter Server 8.x
Refer to the following Broadcom Techdocs to unregister the SRM and vSphere Replication application:
Unregister the Site Recovery Manager Appliance
Unregister the vSphere Replication Appliance