I'm trying to dismantle some wall boards, but I don't know how to remove the pictured bolt - close up attached. Its head has the dome shape of a carriage bolt, but there is a hole in the center, with a square-shaped pin deeper inside. Note the hole is circular and not hex, so this is not an allen bolt. Its a wood-and-fiberglass board attached to a metal frame. I would love to cut up the board, but the metal frame surrounds the entire board, and is attached with these bizarre bolts. Any suggestions or ideas would be most appreciated. Thanks!
This is a pop rivet, not a bolt. It can only be removed destructively.
Drill out the center with a drill bit meant for metal (as opposed to a brad point bit, for instance) until the flange come off. Use a bit roughly half the diameter of the flange.
When the flange breaks free, it will get stuck on the tip of your drill bit, which you will then remove with pliers.