To wipe and reformat a hard drive or partition that doesn’t house system files, access the disk management utility, select the drive, and choose the Format option. To accomplish the same for drives and partitions that house system files, use the installation disc for your operating system, and select the Format option during the installation. Back up important files before proceeding with this process.
To access the disk management utility in Windows 7, click the Start button, type “disk management” in the search field, and click on the Create and Format Hard Disk Partitions link. In Windows 8 or newer versions, start the utility via the Control Panel and the Computer Management screen. Right-click on the desired drive or partition, and select the Format option from the context menu. In the Volume Label field, type the name or a single-letter designation for the drive, select the NTFS files system when prompted, leave the Allocation Unit Size setting at its default value, select the Standard Format option, and click OK to start the process.
For hard drives and partitions with system files, insert the Windows installation disc, restart the computer, and configure it to boot from the disc by changing the boot order while the operating system is starting up. During the installation process, select the existing drives and partitions, click Drive Options (Advanced), select the Delete option, and create a new partition using the unallocated space. After creating the partition, select the Format option, and proceed with the installation.