I have erased a partition of Widows on my IMac using Disk Utilities but it still show on the available drives. It also seems not to have returned the disk space to be used by OS. How can I get the extra space I need?

If my memory serves me right, just open Bootcamp on your mac and select the option: "Remove Windows".
This should do everything for you.

Hope this helps
Grant

Thank You Grant. I did that but was still left with the blank Partition. Anyway I decided to use it as a separate drive and not return those bytes to my main Mac Partition.
Thanks again,
Strap