I guess I would ask why do you need to remove the extender? If he wants it shorter you could just cut it. the part inside the shaft will not effect the playability of the shaft. If you want to attempt to remove it, I would not drill it. You could try heating slowly with a heat gun to see if it would break loose, but it is tricky. Graphite shafts are made of epoxy resin and fiber and when you heat the shaft too much, the epoxy resin in the shaft will break down and become damaged. You could heat a hot rod and heat it from the inside, which would little the heat exposure somewhat to the outside of the shaft. If it were me, I would only try the hot rod method and be very careful not to heat to much.