Hi and
to the forum.
Unfortunately, I don't think there is an easy way to disable the beeping on the VEC300 controllers.
Dismantling the controller and physically disconnecting the beeper unit
(or possibly blocking its sound outlet hole to quieten it) may be the only way to achieve it.
However, dismantling the controller would probably invalidate the warranty.
It would have made a lot more sense if it had been programmed to only emit the 15 beep brake warning code when the throttle and the brakes were both activated simultaneously.
Then, while braking it would warn you that you still had the throttle partially
(or fully) applied, and it would also warn you if you inadvertently tried to accelerate while the brake was still applied.
Alan