Once you have the grip panels off, I assume you are talking about the large pin that goes through the grip.
Spray a little penatrating oil on it, let it sit for a while.
Then get a punch that fits the pin, put the grip on a pin block (or piece of wood with a hole drilled into it for the pin) and hit the punch with a BFH (Big Friggin Hammer). It will come out, you just need to hit it hard enough.
Best regards, John K
