I can't seem to find an option in itunes preferences so that when I delete a song from the itunes library to also psysically delete it from the hard drive.
You can use this method to move your iTunes music library to a new location, delete the old library folder (including songs you've deleted from the library but not moved to trash), then - if you want to - move the library back to it's original location... tedious, but a nice way to clean up a bit every now and then if you have a much larger iTunes Music folder than the contents of your iTunes library would indicate... 😉