Delete with a good redirect to /wiki.html with a 30 second splash page that states the page no longer exists due to old info or never did exist.

I've had 6 editors point to obsolete pages so far this year, so I say either change the info and make it relevant or delete them if there is no useful info on them.

The page said "obsolete" but the editor didn't care, cuz it made his point valid. I showed him the updated wiki, and he still hung onto the old page he found. 2 days later, he was blocked for other reasons.