OrCAD PCB Designer PSpice
You should probably edit the device footprint itself.  If you right click then select superfilter then check symbol you can hover over the part to get its name.  Or you can select the part, right click and select show element and it will give you a ton of information, one of which will be the part name.  Then go look in your library folder for the .dra file with that same name.  You can edit it there and then update symbols.  It might be better to make a copy with a different name and assign that to your "special part".  That's the better practice way to do it.

If you don't feel like doing that, or you're just messing around go to tools->padstack->modify design padstack.  Then select the pin you want to modify, right click and select edit. That will open the padstack editor.  You can make your changes here.  You have to make sure to do a File->update to design in the padstack editor to see your changes.  This is the hacky way to do it ;)