If it's like most pressed on steering wheels first remove the retaining nut and then just have a helper pull up on the wheel while you smack the end of the shaft with a brass hammer. The shock should overcome the press fit.
Variations on that theme include using a long nut, thread half way onto the shaft and put a bolt in the other end, tighten and smack that with a steel hammer.
I've even seen guys just smack the shaft with a steel hammer, which might ruin the threads... that's how the the nut thing came to be.
Of course, all this depends on if the wheel is pressed on like the later ones.
