I'll assume that the wire leads are the same gauge as the winding-- actually, the same piece of wire (or wires, if wound in parallel). If so, making them shorter would increase performance. The length of wire in the windings for 13 turns is relatively short. If you can decrease the total wire length by, say, 3% by removing the excess leads, then you'll get a 3% increase in torque and power due to the lower resistance (with everything else being equal). There will be no significant change in the RPM.

You don't need to attach the remaining leads directly to the ESC as long as you use much heavier wire in place of the lead length that was removed.