You could try soaking the paddle handle in some boiling hot water for a while.. and then see if it will twist off.. or.. maybe a hair dryer.. or if that fails...
Just get a hack saw and saw it off at the length that you want.. Then cut, poke, grind, pry until you get the piece of shaft off the handle.. and if you butcher it in the process see if your local Naish dealer can order you a new handle.. They shouldn't cost much..

DJ