AFAIK KiXtart DEL won't delete files from subdirectories (the "/S" flag means delete system files) so if you really mean that you want to delete *.tmp files from anywhere on the drive you will need to use the DOS DEL built-in:
Code:
Shell '"%COMSPEC%" /C DEL /S /F C:\*.TMP'



NB, I checked this using DOS DIR, and it matched suffixes such as ".tmpl" which start .tmp, so be careful.

The problem is that this will take a very long time to run, unless you can limit the scope of the search.