Erased...Maybe?

I was finally able to call home today after what seems like months. Oh wait, it's been months since I was able to call. Duh! Anyway, I was able to talk to almost everybody. My niece though wanted to talk to 'McGyver'...aka...the husband. They know that he's a computer geek so everytime they have a computer related question they usually ask me to ask him. This she needs help on how to erase hard drive because she wants to sell her computer. She said she already erased the files but she's doesn't know how to erase the hard drive itself. She can take it to a computer store but it will cost her. Unfortunately, she's not in luck because hubby was out. I told her I'd ask the husband to email her what to do so she doesn't have to pay anyone to erase the hard drive of her computer.