If you ever have to remove a link from Google's search results, there is a very good blog to help you: http://www.canig.com/
The main trick after removing the offending page/document from your website is returning the correct error code. Google wants to see a 404 error returned when you browse to the url. http://www.canig.com/ has a tool where you can paste your link to verify you are getting the correct responce.
To use Google's Webmaster Tools, you have to verfy you have access to your website. This is very simple if you have access to your DNS record. Google will provide you with a snippet you can paste into a txt record. It usually only takes a couple hours to take effect. Once you verify your site, you can select your site and go to Optimization>Remove URL in the left pane.
Again, make sure you are returning a 404 error when you make the request.
