VMS Help CMS, DELETE, CLASS, Restrictions  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    o  You cannot delete a class that contains any element
       generations unless you specify the /REMOVE_CONTENTS
       qualifier.

    o  You cannot delete a class that has read-only access. (Use the
       MODIFY CLASS/NOREAD_ONLY command to change the access to the
       class.)