Hi newhandle,
you can use find for this:
find <directory to delete from> -mtime +5 -exec rm {} \;
Be careful with this - it deletes everything not modified for 5 days or more in the specified directory. It's always as well to do a:
find <directory to delete from> -mtime +5 -print
first, just to check that the files returned are indeed the ones you want. If not, it's possible the specify certain files like:
find <directory to delete from> -name '*.txt' -mtime +5 -exec rm {} \;
Replace *.txt with whatever filename/extension combination you require.
Hope this helps.