The pin that holds the pedal arm on needs to be driven in further before it can be driven out. Give the rounded end of the pin a view good whacks with a hamer, and then try to drive it out by smacking the threaded side.
This is counter intuitive, but it works. I think what hapens is that the pin becomes coroded to the shaft and will not budge, well at least not easaly. Driving it in further breaks that bond so that the pin will move when you try to drive it out.
I have found that this methoud works even on the most stuborn crank pin.