QUOTE(RH-Calvin @ Feb 25 2014, 12:28 PM)
Google Disavow tool helps you to track the spam or bad backlinks of your website. It does not delete the links for you. You need to manually contact the webmasters to get your links deleted.
Disavow tool help us when we are not able to remove backlinks manually then you can upload this type of links on disavow tool to not consider as a backlinks to our site. So basically it is blocked our bad backlinks which we upload on disavow tool.