I just replaced mine bulbs to LED in the doom. I don't know if it is exact same as yours, but this is how mine worked. First, I must say......be careful taking out anything plastic in colder weather as it is more brittle.

So push the whole unit towards the rear of the vehicle. Then pry/pull lightly on the front. The front is placed in with two tabs and the rear has a "L" plastic piece the keeps it flush with the headliner.

Good luck. If you run into problems let me know and Ill take mine out and take a picture. It is a 30 job to take out when done correctly. Remember whole assembly. No trim pieces pulled.