You should, with dry hands/palms, press the palm of your hand, with your weight behind you, twist off the hub. You should be able to turn the centre of the hub counter-clockwise.
Try all hubs first, one will 'give' a little and you'll see how they come off.
The thread for the hubs is plastic - so, if you're to hit with a rubber hammer, hit it very gently! Try a major effort with your dry palm first.