There are various reasons why Google might still still have unpublished content in its index.
The first thing that you should do is verify that the offending page/URL is returning a 404.
If it is returning a 404 Google should notice that (eventually) and remove the page from its results on its own. However, you can use Google Webmaster Tools https://www.google.com/webmasters/tools/removals to explicitly request its removal from the index.
The issue should resolve in a day or so.