removing fan from water pump

hey so I have a 67 Plymouth Fury 3 VIP and I was wondering, after you take out the four bolts bolting the fan to the water pump, how do you get the fan off? There is a center "bolt" with a circular head that cannot be removed. any ideas would be helpfull, thanks

You're kidding, right?

If you're not, that's not a bolt. It's the water pump shaft. tap the fan base a little around the pulley.

This must be a joke...