Does anyone know how to remove a speed limiter from a car?

a tuner

Depends on the car, but typically computer reprogramming.

really big tires

a NOS sticker on the rear bumper is worth 5.8 mph top speed

If you need to ask, you shouldn't be doing it.

alphalanos, best response!

I think you should get it to speed uphill (may be hard), flip it to neutral, and let gravity take it downhill. You may just break your speed barrier if the slope is just right, and no cats, dogs, or children get in the way.