For some reason a track on a midi file is being imported as a piano staff. It's a tenor voice part. How do I change the staff to show just the treble clef and remove the bass clef?
Go to the Edit|Instruments... menu item. It opens a window that allows you to add/remove instruments and staves. In this case, you would highlight the bass stave and click on the Remove button.
Another technique is to add the "instrument" you DO want to the score, copy/paste the notes into it, then discard the original staves. That way you automatically get the right playback sound set up for you.