Also check URL removal explained, Part I: URLs & directories
As that article suggests, you can remove directories (and whole sites) in Google's Webmaster Tools. This might be quicker than robots.txt initially, although you will need to use robots.txt as well.
Keep the noindex meta tag to avoid your page appearing at all in Google's index. A robots.txt only solution could still allow URL only links from appearing in the SERPS.
Using robots.txt to remove the "http://www.example.com/getridofthis/" directory...