The DELETE COLLECTION command deletes a collection and,
    optionally, all members of the collection.

    Because a collection is a controlled element, CDO freezes
    previous versions and allows you to delete only the highest
    visible version.

    If a collection is a member, you must delete its owners before
    you delete the collection. If the collection's immediate owner
    is a member of another element, you must trace the relationships
    back until you reach the element that has no owners and delete
    elements one by one, in sequence of ownership.

    If you attempt to delete a collection that owns a version in
    a different branch, the version must be the latest version in
    that branch. Otherwise, an error will occur. See the Oracle
    CDD/Repository Architecture Manual for complete information on
    branch lines of descent.