If you have ever installed VMware’s Site Recovery Manager 4 in a Many to One failover configuration, you know that a single SRM installation can multiple Site IDs. This allows remote SRM installations to pair up with the single SRM installation using an appropriate Site ID. Think of it like a SQL server with multiple instances on it. Creating multiple Site IDs during installation is accomplished using additional CLI parameters.
Sometimes there are times when you need to DELETE these instances (actually unregister them from VirtualCenter). There really isn’t a way to remove them via a GUI or even a CLI command to do it. Fortunately, the process is pretty easy.
After uninstalling the SRM Site from Add/Remove Programs, you need to point a browser to your vCenter Server.
Https://<VCServer>/mob/?moid=ExtensionManager (Or choose Managed Object Browser from the main menu)
Log in as an administrator with access to VC and SRM.
Note the name of the Site you want to unregister and choose UnregisterExtension.
In the Value Dialog box that pops up, enter the name of the extension you would like to unregister and click Invoke Method.
At that point, you are complete.