How do I make my MacBook start up like it's new out of the box?

I'm not selling it or anything, so I don't care about wiping it. I just want to be able to turn it off, then back on and have it start back up the way it would bran new out of the box. I did this years ago and cant remember how now, or find anything that simple on the web. I remember it being easy, like just a key command like a command+C boot or what not.