The DELETE GROUP command deletes a group from a CMS library. If
    the group is not empty and the /REMOVE_CONTENTS qualifier is
    not specified, or if the group belongs to another group, CMS
    returns an error and does not delete the group.

    Even though a group is deleted, records of transactions that
    created and used the group are retained in the library history.
    You can reuse the deleted group name to create a new group.
    However, there is no distinction between the two groups in the
    library history, except that their transactions are separated by
    entries for DELETE GROUP and CREATE GROUP commands.

    To determine which elements and groups belong to a group, use the
    SHOW GROUP command with the /CONTENTS qualifier.