'Unregisters a VM from the Host System.'

def _unregister_vm(self, method, *args, **kwargs):

    vm_ref = args[0]
    _get_vm_mdo(vm_ref)
    del _db_content['VirtualMachine'][vm_ref]
    task_mdo = create_task(method, 'success')
    return task_mdo.obj
