I found this through Google and my anticipation built as I read through the pages but was left full of suspense when the thread just ENDED without a resolution. So, after performing the same operation, I signed up to share my results in case someone else has the same problem of a stuck sb-600 that they can't remove from the camera.
Removing the 4 screws on the bottom works. That's the short answer. I was fortunate enough to find a very tiny, very short screwdriver in a watch maintenance kit I picked up for about $3 off Amazon awhile back. It's like 1.25" long and smaller then the normal electronics tweaker screwdriver. Eyeglasses screwdriver sized. I work in electronics so I've got a bunch of those little tweakers and was prepared to either bend one to 90 degrees or cut the head off, but it didn't fit the head of the screws in the flash anyways. The small, tiny screwdriver I found was small enough to almost fit the space available between body and flash, with just the tiniest bit of angle of attack. I used a tiny pair of vice grips to grasp the driver and push in. There's a little bit of resistance from the threads having cut into the virgin plastic at the factory as you start to turn the screw, but they were removed without any damage to the screw heads. They're about 5/16" long, they'll drop out pretty easily if you're not careful, and as soon as you have two out, the flash body will start to flop around a bit, and as you remove the fourth, it will topple and fall. I worked on it while it was laid on the bodies side, which I assume most others would as well. The wires inside, you can't really just unplug and disconnect the flash from the foot. There IS a plug, but there's also a few wires that are soldered in place, so don't yank the body off or let it fall and topple too hard.
I should have taken a picture for reference, but I didn't. Maybe when I repair it I'll remember to take pics and post again. Towards the front of the base, is a small 1/2" long x 1/8" widepiece of metal. There's a screw on either side holding it in place. Poking through the center is the tip of the retention pin. If you stick a tiny flathead screwdriver, eyeglasses repair kit size, into the foot, you can lift that up and gently slide the assembly out of the camera's hot shoe. What has happened is the plastic coupling between the lock switch and the retention pin has broken. I imagine I broke mine by my ham fisted over rotation of the lock switch "Gee I wonder if this will turn all the way around". It shouldn't.
I now need to find a replacement piece coupling. I haven't started looking yet but I imagine it should be readily available online, if not I'll order from the LCS. It looks like you remove the two tiny screws that hold that thin strip of metal in place, and another screw or two by the lock switch to loosen up the assembly, carefully move this and that around, and voila.
