Need to delete an SAP server which is no longer monitored.
Go to Administration | Agents Agent Status | Deactivate and delete the agent which is no longer needed
Go to Management Server | Servers | Data Management | Look for an Object name that refers to SAP server to be deleted and drill down into it until you find the name. Delete all instances referring to the SAP server name. Click the Delete icon which is a red circle with a minus sign in the middle.