Are you talking about a custom Network Workgroup or a Workgroup via PC properties? They are two different things.
As for the workgroup in PC properties. Trying change "workgroup" to something else. It can be anything like "home" it doesn't matter. Save and reboot. System will be off the Workgroup and on its own group called "home" now.
This really doesn't matter if a Network Workgroup is enabled as that is done from network sharing center. Not PC properties.