If your No Child Left Behind system is still intact, there is a procedure for stopping the beeping. In the IC buses I drove, it varied, but in general, it activated only after turning on your 8 way lights (the yellow and red ones on top, front and back, that flash alternately). After turning off your 8 ways, you shut the bus off. You then have say 30 seconds to go back and press and hold the button until you hear a beep. After that, the alarm is disarmed. Once you've disarmed it, it should not arm again unless you activate your 8 way lights.
You may need to get information on the model of the system and contact the manufacturer for the proper sequence.
Per removing it from the bus, I'm not sure. Mine was already removed.