computer repair

"Single User Mode" AKA root prompt with ⌘ + s

I'll be honest, I've never been a great mac fan-boy. In fact, I'm pretty sure that after my current macbook pro dies, I'll stick with a great PC that has all linux tested hardware and just use Ubuntu. It's not because I hate Mac. I like it quite a bit actually. It's because it's so damn expensive! With that said, I found this awesome looking iMac that was manufactured back in 2002, and their designs are cute and sleek. Unfortunately, It had the pervious user's password still on it. What do I do?!?