Disassembling a bed frame
Just about the only thing you can do is turn the cam 1/4 turn at a time and keep trying to separate the joint. These are usually easy to lock and unlock is why they are used. But if they were over tightened ever or the wood was repaired or even wrong in size like from a factory defect, you could find yourself turning these things back and forth all day because they will only unlock in one specific "sweet spot".

I know these cams can be frustrating and even cause people to second guess clockwise,counter clockwise, lefty loosey-righty tightly and so on.