You can do it easily with diskpart -- BUT be careful that you only type exactly what you want to happen. Open your command prompt box with a right click run as administrator and then type diskpart.
To format a partition you have to go to the disk, then the partition, and then run the format, so
select disk n (where n is the disk number that contains the partition)
select partition x (where x is the partition for format)
Here is a full list of commands and syntax: http://technet.microsoft.com/en-us/library/cc770877%28v=ws.10%29.aspx