Letters pop off, there is a nylon plug that they fit into. Keep them if you can they are a tad more expensive than i expected them to be.
Trim is hooked on a small clip. Clip is sharp on top and rounded on the bottom so, it "hangs" on the top and pushes in on the bottom. Carefully pry it from the bottom.
Having said that, when i took mine apart, i didn't note the orientation of the clips and my body guy removed them. When i reinstalled them, i did so in that orientation assuming it to be the logical way. These are British Cars so there is a chance what i am describing is upsidedown but i don't think so.
Regardless, they will "pop" off.