>How is this done so I can show them?

Well, there's the Help section of the GUI, the Help subcommand of the
command line client (Delete Archive), and the Backup/Archive manual
at http://www.tivoli.com/support/storage_mgr/pubs/admanual.htm .
They really don't need you for this.
If they ever ask you as server administrator to delete files for them,
you can inform them that the capability does not exist within the
server for deleting individual files via supported commands.
(That's not why administrators were put onto this planet.)
    Richard