You Asked:

How do you erase a hard drive on computer? — Howard, San Diego, Calif.

Marshall Brain Answers:

It depends on what you mean by “erase”. If you mean, “how can I blank a hard drive so I can load a new operating system?” then reformatting it would be sufficient. A reformat, however, can leave the actual data on the disk. If someone has enough motivation, they would be able to recover some of that residual data.

If you want to erase a hard drive permanently and irrevocably, you would do that with a hammer. Unscrew the cover and smash the platters with a hammer while wearing safety glasses. The data will be completely destroyed.

If you are looking for a non-hammer approach that leaves the drive intact while removing the data, then what you need to do is overwrite all of your data with zeros. On a large drive this will take several hours, but it is fool-proof. This video explains the process using a program called Darik’s Boot and Nuke: