I assume you need the OBC under the radio and not the guage cluster.
To remove the OBC, slide a credit card underneath it from the front, and push on it from the back. There is a small hole you can fit about two fingers in directly below it. Reach and push it out from the back. once it's move far enough, pull it out from the front.
You can then see the back of the bulbs. A small screw driver and a few turns and they come right out.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>