Slick 60's

How do I remove the original knob on the handle? Already have the handles off. I have tried everything that I can think of. I guess its a BFH next.

If the knob is going to be reused, I used a little heat from a heat gun and warmed up the back of the pin pretty good, and used a wide blade screwdriver to pry it off, if your not reusing just cut it off.

The pin in the back is a press fit, and hard to get off as you have noticed. It has ridges on the pin that are tapered towards it's end so it can go in easily but not come back out. Wondering why you want to take the knobs off?