Is the page itself expendable? Unfortunately you can't deal with it by serving a 404 only to people who come in from the unwanted links, which may be what you wanted to do. Google already knows the URL, and they'll be crawling it independently.*
Option B is to move or rename the page-- and, of course, update all your internal links. Then the undesirable links would lead to a 301. I think g### is sophisticated enough to recognize it as an outdated link, which carries less weight. (Uh... doesn't it?)
* Hm. Food-for-thought question there. Somewhere down the line, will google's next step be to crawl with not only plainclothes UAs but also different referers, to see if that affects the page they get?
You mean the page as it now stands is worthless in rankings and it has no external links that you want to keep? Then there's no reason not to dump it.
Formally it would be a 410, not a 404, since you've removed it intentionally. Don't forget the custom 410 page if you haven't got one already! (I use the same physical page as 404. It's just for humans-- and the default Apache 410 page is scary.)