Unable to Delete Master Server

I am running OpsCenter Analytics 7.5.0.1.  I am unable to delete a decommissioned master server.  I do:

Settings

Configuration

Select the master server for deletion.

Click Delete

Once done, I get a message saying, Operation Completed. The OpsCenter console may take some time to show the updated status.  However, the server is never deleted.  I've waited days, I've restarted OpsCenter completely, I even defragged the DB... it will not go away.

Is there any SQL I can run in the report view to remove it cleanly?