VMS Help BACKUP Command, Qualifiers, /DELETE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Command Qualifier

    Specifies that a BACKUP save or copy operation is to delete
    the selected input files from the input volume after all files
    have been successfully processed. Sufficient user privilege is
    required to delete files. If used with the /VERIFY qualifier,
    files that fail verification are not deleted.