1) Double-click the My Computer icon, and then click the icon for the disk you want to format.
2) Be sure not to double-click the disk icon, because you can't format a disk if it is open in My Computer or Windows Explorer.
3) On the File menu, click Format.
Notes:
Formatting a disk removes all information from the disk.
You cannot format a disk if there are files open on that disk.
If the disk has been compressed, use DriveSpace, or other compression software, to format the disk.