How do you reprogram the ecu on a 2011 Mercedes sprinter to remove the speed limiter?

This requires the ECM software.... you'd have to get it done at a dealership, which is the much cheaper alternative to buying the software yourself (we're talking a couple thousand, easily)... if it's a fleet vehicle, or any type of company vehicle which isn't yours, then the ECM will probably be passWord protected to prevent exactly what you're trying to do.