The DELETE CLASS command deletes one or more classes from a CMS
    library. The class must exist and must not contain any element
    generations unless the /REMOVE_CONTENTS qualifier is specified.
    If the /REMOVE_CONTENTS qualifier is not specified and any
    generations belong to the class, CMS issues an error message and
    does not delete the class. If the /REMOVE_CONTENTS qualifier is
    not specified, use the REMOVE GENERATION command to remove element
    generations from a class before issuing the DELETE CLASS command.

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

    To determine which generations belong to a class, use the SHOW
    CLASS command with the /CONTENTS qualifier.