Broken memory card door/cover

I accidentally broke the top half of the memory card door of my camera off, I have a new door/cover , but how do i remove the old one and attach the new one. I see a pin holding it in place but i cannot figure out how to remove the pin? do i need to remove the camera casing to do this? the photos here dont show that part of the camera so I have no idea if removing casing would allow me to switch this door or not.. thanks