Typically, you would erase a computer’s hard drive with the Windows Install CD, as part of a reformat and reinstall process. Without the Windows Install CD, you are unable to reinstall Windows. Thus, completely wiping out the hard drive will leave the computer in an inoperable state. If this is what you wish to do, you can use a free boot CD to completely wipe the hard drive. Before doing so, it is important to back up your data and be sure entirely erasing the computer is what you want to do.
Download Darik’s Boot and Nuke boot CD ISO (see Resources).
Burn the ISO file to a CD. If you are using Windows 7, simply double-click the downloaded ISO file to launch the “Burn Disc Image” utility. If using earlier versions of Windows, you will need a third-party utility such as MagicISO, Alcohol 120 or ISO Recorder to burn the ISO image to a physical disc.
Insert the DBAN Boot CD into the computer’s CD drive once the burn is complete (or simpy leave it in there). Restart the computer.
Press any key to boot into the CD. The system will launch into the DBAN disc, displaying a text-only menu system.
Press “Enter” to start DBAN. Using the arrow keys, select “Disks and Partitions.” Highlight the drive you wish to completely erase; select it by pressing the space bar. You can optionally press “M” to choose your desired wipe method, based on security level.
Press “F10” to begin completely wiping out the hard drive.