So I had to figure out how to do this, and there wasn't a lot of good information on it and this post was the top result on Google. The top video result was for a Honda Pilot charge door and the Clarity door is different. I'm going to put an answer here because it's actually relatively easy. You need a Phillips head screwdriver and a flat head screwdriver.
There is a removable cover plate that sits between the door assembly and the charger port. Where the door has the latch to close, there is an open space where you can use the flat head or even your finger to pull it out. I did this about a week ago so I'm trying to remember the specifics, but IIRC the charge cover plate has some wires connected to it for lighting up the area when you open the door. It is easiest if you disconnect the plug to those little LED lights and fully remove it. Regardless of whether you leave it attached or disconnect it, you will now see two Phillips head screws on the right side of the charge port door. Remove both of those.
Once you've done that, you can get your hand around the door on the right hand side and with some modest force you can unseat the charge port door. If you've disconnected the cover plate, the door will come right out. If the plate is still attached, you'll need to move the door and the plate around to get the door out around the plate. I found that I was able to get the door out with the plate still connected but I wasn't able to quite figure out how to get the replacement door back in with the plate still connected, so I ended up disconnecting the plate and then reconnecting it. The new door will slide in and be screwed down with the two screws you previously removed.
If you want to disconnect the plate for ease of access, there is a white connector on the back that has two small tabs locking the connector to the plug. A small flat head screwdriver may be necessary to get the tab off of the connector, just be careful not to snap the tab off. I found that the waterproof seal wanted to slide off easily so watch to make sure that that is back in place when reconnecting the power connector. Once the door assembly is screwed into place, the plate will just snap back into place.
