If you disconnect it then it shouldn't matter, the car still has brakes and it is not a legal requirement to have ABS. Therefore they can not fail you. If it has the ABS connected but it don't work then that is a different story. It's the same as if the seatbelts in the back of the car are knackerd you will fail, but....if you take the rear seats out and the seat belts, then they can't fail you as there's nothing not working that should be!