If your speed controllers have BEC (check the instructions), simply remove the RED lead from one of the plugs that goes into the receiver - Only on ONE of the speed controllers though, then the other one will still feed power to the receiver.
There's no need to cut the wire, just lift the small plastic tab that hold the lead into the plug, fold the lead back onto itself and wrap a bit of tape to it to hold it in place. That way you can easily restore the BEC facility if you move the speed controller into another model.
Hope that helps?
Eddy