Blocked Sites FeatureNearly from 1 year ago blocked sites feature is not in online, Google officially declared that they are discontinued this feature.
By using Chrome extension or maybe some unofficial extensions for Firefox or Chrome only we can block the search results in Google.
The blocked sites feature is released in March 2011. You can notice Block all www.abc.com results below the url in results. By clicking on that link, you can block those pages or sites appearing in future on your system.
At that time, Google said that it was adding the feature to searchers for more control.
This feature is added to satisfy the user to get more unique and relevant results. If the user dis-satisfy, he can block the results of a particular domain. A part from this after getting the list of blocked sites feature from chrome extension, Google may reduce the priority of the blocked sites list. It consider as these are the sites which are dis-satisfied or unrelated results displaying on SERP.