How do you remove a bus speed limiter?

If it's a vehicle you own, you simply take it to a dealership which services the type of motor it has (Detroit Diesel, Cummins, Caterpillar, Volvo, etc.) and have them reprogramme the speed controls in the Engine Control Module. Or you can spend thousands for the engine software and do it yourself with a laptop and the appropriate connector to go from your laptop to the ECM.

If you don't own it, you have no business tampering with someone else's vehicle, nor do you need to go any faster - a bus driver in New York just killed 13 people because he wanted to run at 78 MPH and lost control of the bus he was driving. Most buses I've seen are driven both at high rates of speed and very ineptly. If your company governs their buses down, that's a good thing - both for the drivers and for the passengers who place their lives in the hands of often-underqualified bus drivers.