Replacement key cont'd

Hi guys, I recently posted about my broken key for my 1991 tt, tried contacting Mitsubishi & gave them the vin number but they told me because it was an import they cant help with a replacement key. Another locksmith in Glasgow says he can cut one if I take him in the barrel from the door. I’ve removed the door panel but don’t have a clue how to remove the barrel & can’t seem to find any instructions on google. Can anyone help ?

Thanks guys