As a long time master mechanic, I really have to advise against removing the positive cable-always remove the negative cable from the battery. There is always a chance of damage when removing the positive, for instance if your wrench contacts any grounded metal of the car (which is just about everything) the result may be “just a spark” to you, but could easily destroy any circuits in the car. Hit the same metal removing a negative cable and nothing will happen. Be careful out there!