1st off its a "tight fit pin". Depending on the gun, you will need something pointed to push it out, mine are so damn tight i need a hammer and punch.
2nd, the end of the pin is not round, it's like a half moon, and has a depression on it. the slide stop spring falls in that depression, keeping it in place. it won't come out its own.
based on your issue, this is the fix you need. you wont have the slide go to side lock anymore at all, so make sure you know your round counts. However, if you're going to slide lock on a stage, you've probably already done something wrong!
Gotcha. Makes sense now.
Much appreciated sir.