It's called a roll pin. You can watch some youtube videos. Basically you pound it in and out using a hammer and punch that is just the right diameter.

Roll pin punch works great.

LTG : )

You need a roll pin punch set, vise, and a hammer. Here's the roll pin punch set:

https://www.amazon.com/Pieces-Gunsmithing-Removing-Automotive-Jewelry/dp/B07JNS1ZF7/ref=sr_1_6

Depending how much space there is between the two metal faces you might want to put a shim between them. I have a variety of thin washers I use to fill up any gap between the faces and the fiber link. If you try to knock out the pin with a gap in there you risk bending one or both faces so they're no longer parallel which can make it harder to reinstall the pin. If there's no gap then the blow from the hammer all goes into moving the pin and not into bending the metal faces.

Also, don't completely remove the roll pin. If you back it out slowly you can stop when there's just enough clearance to replace the link and the pin is still held in place by one of the faces. Then it's much easier to tap back into place, again with a shim to fill the gap.

/Mark