Originally Posted by dabac

Freewheels tighten by pedalling action. They can be on wickedly tight.
The preferred method of removal is to find a sturdy vise mounted to a sturdy bench anchored to a sturdy wall. Then stick the freewheel puller in the vise, put the wheel on top. Grasp rim like a bus driver turning hard left. Failing that, stick a cheater bar on the wrench, position the wheel in a corner so that unscrewing action will force it against a wall and twist. Or stomp on the cheater bar.