Can't you just snip/disconnect the speaker/bell wire? I did this back when I had a truck and often had to maneuver with open doors (at very slow speeds) - the "door open warning bell" was so annoying that I just pulled its wires.
AFAIK the warning tones don't come from the car's stereo speakers but have its own speaker.
AFAIK the warning tones don't come from the car's stereo speakers but have its own speaker.