if you are talking about the fat pin that goes through the shaft to locate the two shoes, i just left mine in when i rebuilt my coupler. i replaced everything else but didn't see any wear or damage to that pin and i didn't have a press at the time and didn't want to mangle the shaft trying to get that pin out.
If the pin is not worn, leave it in. The new coupler seals will stretch over the pin. Don't try to stretch an NOS original style coupler seal over the pin, it will split the lip.
Top is an original seal, other two are replacements.