'Delete a child and parent storage groups.
:param serial_number: the array serial number
:param child_sg_name: the child storage group name
:param parent_sg_name: the parent storage group name
:param extra_specs: the extra specifications
:param device_id: the volume device id
:param move: flag to indicate if volume should be moved to default sg'

def _delete_cascaded_storage_groups(self, serial_number, child_sg_name, parent_sg_name, extra_specs, device_id, move):

    if move:
        self.add_volume_to_default_storage_group(serial_number, device_id, '', extra_specs, src_sg=child_sg_name)
    if (child_sg_name != parent_sg_name):
        self.rest.delete_storage_group(serial_number, parent_sg_name)
        LOG.debug('Storage    Group    %(storagegroup_name)s    successfully    deleted.', {'storagegroup_name': parent_sg_name})
    self.rest.delete_storage_group(serial_number, child_sg_name)
    LOG.debug('Storage    Group    %(storagegroup_name)s    successfully    deleted.', {'storagegroup_name': child_sg_name})
