The flywheel is held on by a nut, but its also on a tapered, keyed, shaft. Remove the nut (which may be left or right hand thread) gently (very gently) prise the flywheel with 2 screwdrivers, put the nut until the threads are covered and give the shaft a tap with a hammer, but don't overdo it! Normally we use a proper extractor for this but my method should work if you're careful. To stop the flywheel rotating I use an air gun to shock the nut off but a lever through the fins may work - but they are easily fractured.
John
December 2007