You want to discard your old computer and you want to securely erase the data from your hard drive. what can you use to do this and what is the processed called

Factory reset will NOT completely erase your hard drive. The correct term maybe be reformatting or drive wiping. Even though it may take a lot of effort, recovering and stealing data from a hard drive after doing this is still possible. The best way is to get a hard drive shredder. But they can be expensive. You can use a drill to cut holes but with special equipment, a thief can still steal data so the best way may be getting a powerful magnet data wiper but if not possible, get special disk eraser/reformats that reformats the drive so much that it is unreadable. For disposing the rest of a computer, you might have to look online or a special computer/store manual on where specialized computer recycle dumps are located.

It is called "Factory Reset" and all computers are different, plus its not some simple command you put in, you wouldn't want a child deleting all your hard work.

The best bet is to look up your type of computer + factory reset on google.