How do I un-partition a hard drive?

When I tried to re-partition my hard drive to give my C drive another 2 gigs of space, it said my other partitioned drive was “bad” in Partition Magic. How do I erase this original partition and start from scratch, as if I had my original 20gig drive as a whole instead of it being partitioned? Please reply to tborish@kent.edu.

Thank you