The Special:Categories page shows all categories that contain at least one article, not taking into account whether the category has its own page or not. Try this: click at the red link, it will take you to the edit box of the category page. There, click Cancel or the "category" tab at the top of the page. It will take you to the category page, where you will see the list of articles that are still in this (as you say "abandoned") category. As soon as all those articles have their [[Category:ThisAbandonedCategory]] removed, the category will disappear from the list. (Or, that is the way it should work, at least.)
HTH, -- [[ :cs:User:Mormegil | Petr Kadlec ]]