Detaching components from convenience center

I'm working on my truck's interior, and I've decided to replace the courtesy lights and radio, both of which are hooked into the convenience center (left hand side, near fuse box, on firewall). I've tried unclipping the boxes the wires run into, and I've tugged on everything (not too hard), but they won't come out. What am I missing? How do I remove components from the convenience center?