I think he wants to take the taillight assembly apart.
I looked at it, but never tried because I was scared I was going to break the lens. But you could try baking them in the oven to melt the glue. and then carefully pry the lens off.
I have a bunch of dirt in my driver-side taillight, I just ended up buying a 'new' taillight from eBay. I suggest you do the same if you have the same problem as me.