trying to remove a part from a score

I am trying to remove the bass vocal, and the bass clef part from piano from a score. I found the parts, delete parts feature. When I do this, i generate the parts, delete the bass vocal. It deletes it from the generated individual parts, but not from the overall score. My goal is to grab some of the existing scores, and simplify them. To open an existing score that has many parts I don't want, remove them, and have say just the piano treble clef as the melody line, and one or two vocal parts.

thanks!