You really don't even need a script, just add a one
liner to cron directly:
15 1 * * 1 find <pathname> -mtime +30 | xargs rm -f
or
15 1 * * 1 find <pathname> -mtime +30 -exec rm -r {}\;
Will remove all any files or directories under <pathname> older than 30days on Mondays at 1:15 am.
pathname of course can be a directory or files or wildcards, etc...