How to securely delete files on Windows PCs using Cipher

So, here’s how you permanently and securely remove files from your Windows PC.

Uninstall all the software programs that you don’t want to leave behind. Some software keeps local files (e.g. caches) that are not stored in the places where you would normally delete.
Delete the files you want removed.
Run cipher as follows:
You need a command window to run this program and it needs to have Administrative rights. So press the Start Menu (bottom left) and type “command” – as you do so, you will soon see “Command Prompt” appear in the search results above. You want to right click on this option and select “Run as Administrator”.
You then will get a command window. Simply type in the following and press return:
cipher /w:C
Assuming that the drive you want to clear is the “C:” drive. If you have a different one then replace C with your alternative (e.g. “cipher /w:D”).

You will then see that Cipher is doing its thing.

Depending on how large your hard drive is, this process could take a while as it has to read and overwrite every unallocated sector on your drive – three times. So let it run overnight perhaps. But once its done, you can sleep a little easier about your personal / private data.

via How to securely delete files on Windows PCs using Cipher – Matt Hopkins.