You do have the third brakelight assembly off the car? Grabbed the "head unit" with both hands and gently wiggled it off the pedestal??
I broke the tab on mine and replaced it with gray double-stick tape, just a 1" pieced from the removable cover to the "head unit" as a splice. With a gray interior and therefore gray 3rd light, the gray tape blends in nicely.
I replaced the bad bulb a couple days ago and with the tape let me release the clip on the left side, then with the tape still attached, rotated the cover back enough to replace the bulb. Snapped the cover back in place and pushed it back onto the pedestal under the rear window. Easy - peesy.
I broke the tab on mine and replaced it with gray double-stick tape, just a 1" pieced from the removable cover to the "head unit" as a splice. With a gray interior and therefore gray 3rd light, the gray tape blends in nicely.
I replaced the bad bulb a couple days ago and with the tape let me release the clip on the left side, then with the tape still attached, rotated the cover back enough to replace the bulb. Snapped the cover back in place and pushed it back onto the pedestal under the rear window. Easy - peesy.