Add task to gracefully terminate domain class instances

pvc.py

@@ -767,6 +767,9 @@ def undefine_vm(dom_name, dom_uuid):
         click.echo('Waiting for cluster to update.')
         time.sleep(3)
 
+    # Gracefully terminate the class instances
+    transaction.set_data('/domains/{}/state'.format(dom_uuid), 'delete'.encode('ascii'))
+    time.sleep(2)
     # Delete the configurations
     click.echo('Undefining VM "{}".'.format(dom_uuid))
     transaction = zk.transaction()