Open the Start menu, click "Control Panel," then click "System and Security."
Windows indexes a list of your installed hard disks and allows you to access them from the "Computer" menu. Although your primary (C) Windows partition cannot be formatted without losing Windows, additional partitions on your hard drive or other usable hard drives connected to the system can be formatted at any time without loss of your operating system.
Click "Administrative Tools," then double-click "Computer Management."
Click "Storage," then "Disk Management."
Right-click the label of the hard drive you would like to erase.
Click "Format," then click "OK" twice.