'Removes the specified volume from Cinder management.
Does not delete the underlying backend storage object.'

def unmanage(self, volume):

    try:
        qos_policy_group_info = na_utils.get_valid_qos_policy_group_info(volume)
    except exception.Invalid:
        qos_policy_group_info = None
    self._mark_qos_policy_group_for_deletion(qos_policy_group_info)
    super(NetAppBlockStorageCmodeLibrary, self).unmanage(volume)
