For the longest while I was searching for the proper procedure to remove the centre mounted brake lamp. I wanted to remove the tint from my car, but wanted to find the proper way to remove it. I searched high and low for a tutorial, but came up empty. I did find something in a shop manual, but it wasn't very clearly explained. It's really shocking how little tutorials there actually are out there for the 2G 6, so I wasn't surprised. I actually came to this forum to try to request some help, but while going through the signup process, I came across a site where some guys needed to remove the lamp to put on tint. They got some help, and I decided to try my luck with those instructions. Lo and behold, it all worked! So, since I've seen where others on several Mazda boards have unsuccessfully asked this question, I'm giving back to the community by posting a tutorial on how to do it.
1. Gently lift one side of the brake lamp housing upwards enough that you can get your fingers under it, palm facing up.
2. Then slide the fingers of your other hand under it so that both hands are at both sides.
3. This is the scary part. Pull up on the lamp housing as far up as you can but do not yank it aggressively. You will hear two popping sounds. This is the sound of the front clips on either side of the lamp housing being released.
4. Then, grip the lamp housing with both hands and pull towards you without aggressively yanking at it. It will then pop out of the rear clips. The circuitboard assembly will separate from the lamp housing, but do not be alarmed. This is normal.
5. The circuitboard at this point will still be connected to the power wires. Unclip it from the wires using a pointed object like a precision screwdriver if you need to (the clip is very stubborn).
6. The two pieces of the assembly are easily fit back together...
...by aligning the rear clips...
...and pushing the tabs in place:
7. Plug the wires back in place and then align the rear tabs of the housing with the openings that are close to the rear windscreen.
8. Push down on the rear of the housing (with your finger tips touching the rear windscreen if possible) until the rear clips snap in place.
9. Push down on the front of the housing until the front clips snap in place.
I hope this helps anybody who needs to do this for whatever reason.