Well, the scene wasn’t totally cut, as the above still shows, you can see about a second from it in the film if you look closely among all of Joel Schumacher’s flash cuts. But there’s no doubt that you were originally intended to see a much more graphic version before the 1987 vampire coming-of-age horror The Lost Boys went before the American censors the MPAA – or maybe Schumacher wanted it cut himself. Speaking to ‘Yahoo!’, star Kiefer Sutherland talks about this scene:
“There was a scene that actually didn’t make the movie that I was really, really excited about, mainly because it was just so violent I couldn’t believe that we were doing it. It’s sort of in the movie — they cut around it — but there was a guy on a beach and he was bald and they had made a prosthetic cast of his head. And the part of the scene that I loved the most was literally, it was like a cake: I ate the whole back of his head off and blood just went everywhere. I had been directed to just smile like a child having cake, and the two images were so frightening and scary.”
Sadly, it seems unlikely that the footage exists. Considering the popularity of the film, we’d have probably seen it by now if it did.