You're trying to separate the inner and outer shafts?
I like to hold it vertically by the inner shaft, letting the hub end hang down near the ground over some sort of padding (wadded up blanket or some foam rubber). Hit the back of the cup with a dead blow at a downward angle, turning the axle a bit each time. Eventually it will come loose and fall down onto the padded surface below – watch your knees, shins, and toes!