To start with the motor shaft and blower wheel are left handed threads.

I use a vis grip to hold the shaft of the motor from turning. Then turn the blower wheel (remember left hand threads) with a wrench or sometimes I can put on a pair of gloves (to keep from cutting my hands) and spin the blower wheel off by hand.

Sometimes the blower wheel is on there so tight that I have to bust it off with a hammer and then replace the blower wheel with a new one.