def del_application(self, application, sync=True):
        """
        delete application from this OS instance
        :param application: the application to be deleted from this OS instance
        :param sync: If sync=True(default) synchronize with Ariane server. If sync=False,
        add the application object on list to be removed on next save().
        :return:
        """
        LOGGER.debug("OSInstance.del_application")
        if not sync:
            self.application_2_rm.append(application)
        else:
            if application.id is None:
                application.sync()
            if self.id is not None and application.id is not None:
                params = {
                    'id': self.id,
                    'applicationID': application.id
                }
                args = {'http_operation': 'GET', 'operation_path': 'update/applications/delete', 'parameters': params}
                response = OSInstanceService.requester.call(args)
                if response.rc != 0:
                    LOGGER.warning(
                        'OSInstance.del_application - Problem while updating OS instance ' + self.name +
                        '. Reason: ' + str(response.response_content) + '-' + str(response.error_message) +
                        " (" + str(response.rc) + ")"
                    )
                else:
                    self.application_ids.remove(application.id)
                    application.osi_ids.remove(self.id)
            else:
                LOGGER.warning(
                    'OSInstance.del_application - Problem while updating OS instance ' + self.name +
                    '. Reason: application ' + application.name + ' id is None'
                )
delete application from this OS instance
        :param application: the application to be deleted from this OS instance
        :param sync: If sync=True(default) synchronize with Ariane server. If sync=False,
        add the application object on list to be removed on next save().
        :return: