Roll the window crank until the rontating ball part of it is at the 12 o'clock position, look down behind the crank and you should see a round pin at the base, with a small screw driver pry the pin off (be careful not to hurt the window crank handle itself). Once the pin is off, the handle pulls right off with ease.
(If you see the bottom side of it as opposed to the top, someone has installed it wrong and you'll have to attack it from the 6 o'clock position).
Hope that makes sense.