Jim,
Seems to me (if I remember Tutor correctly) that you can execute an external program from a Tutor part program with the 'exec' command. You can build a simple batch file that will delete the file in question, and execute it using 'exec (name.bat)' at the beginning of your part program. This should be in the Tutor manual, probably under the heading of Advanced or Deappl Language.
Tom