WIP: clean up after user and org user delete

pkg/services/sqlstore/user.go

@@ -399,6 +399,7 @@ func DeleteUser(cmd *m.DeleteUserCommand) error {
 			"DELETE FROM org_user WHERE user_id = ?",
 			"DELETE FROM dashboard_acl WHERE user_id = ?",
 			"DELETE FROM preferences WHERE user_id = ?",
+			"DELETE FROM user_group_member WHERE user_id = ?",
 		}
 
 		for _, sql := range deletes {