I am trying to remove the rear light cluster in the bumper of my 2011 R56, to replace a bad bulb, but I can't see how to release it from the rear.

Here's a photo. There seem to be multiple tabs that might need opening. Advice would be welcome!

 

I used a small flat head screwdriver to pry the big tab towards the front of the car. The biggest one in the pic. I think there are 4 per light. Then the light fixture slides out from the bumper from the inside.

 

Which one do you mean by the biggest? There are three in the photo: one to the left, and two to the right - are you referring to the top one on the right?

 

Yes, the top right one in the pic.