Ahh... there we go...
The problem is you're not destroying your camera... you're destroying some other camera ;D
If you look at your camdestroy line, you'll see that it refers to
camera. All the other lines (most importantly the camcreate one) refer to
_camera. The underscore is very important, as
camera and
_camera are two completely different objects!
So to destroy your camera, simply change the line to:
camdestroy _camera
However I would also suggest adding a line to terminate your camera, eg:
_camera cameraeffect ["terminate","back"]
camdestroy _camera
OFP used to have issues with destroying cameras before they had been terminated. This may have been fixed in recent patches, but better safe than sorry
Hope that helps you out...