While pushing in on the firing pin, lift up on the punch holding the pin in and slide the firing pin retainer out of the slide.

Firing pin is under pressure. While not enough to hurt you, it can fly out across the room. For those with series 80 styles, you can lift up on the firing pin block and it will catch the firing pin as you take the retainer plate off.

Series 70 styles will not have the pin block to press down on so you just use the punch on the firing pin.