Use either a punch and hammer or spring loaded punch. There is a certain side in which it needs to go through.
You will notice that one side is knurled, and one is perfectly cylindrical, punch from this one. If you apply force to the knurled side(one with ridges) you will never get it out.
Those ridges keep the pin in the frame preventing it from falling out. You want to punch out from the smooth end and put it in from the knurled end.
Certified for: Planet Eclipse, DYE, Empire/Invert, Tippmann, BT, Bob Long and Dangerous Power with 13+ years experience in the industry, ask me anything, I know more than anyone.