This guide contains the basics on how to wipe a hard drive, using the multiple tools available

See also

Internal Hard Drive

Wipe Before Windows OSD

External Hard Drive (Toaster Method)

Obtain a “toaster” and the hard drive to be wiped. Setup the toaster and hard drive

Wipe Using Windows File Explorer

Wipe Using Windows Disk Management

Windows 7

Windows 10

Either Internal or External HDD

Using the Multiboot USB tool

Alternative to the Ultimate Boot CD method