Reset laptop completely?

Just wanted to ask how to completely reset a laptop. And not on the state of purchase but so that EVERYTHING is gone, including the operating system. That you can add everything all over again.

That should help

REMOVE THE HARD DRIVE AND CONNECT TO A DIFFERENT COMPUTER AND THEN ZERO THE DISK, THEN YOU Can't CREATE ANY DATA AND THEN REINSTALL THE OS.

PS. THE ZERO CAN ALSO TAKE A WEEK!

Capitalizing is rude. You yell at the users.

Uh what?