BlockSite is an extension, which automatically blocks websites of your choice. This extension will also disable all hyperlinks to these websites, by just displaying the link text without the clicking functionality.
You can add and or remove websites, you don’t want to visit ever again, via the BlockSite Preferences.
You can open this window by clicking on the options button of BlockSite in Tools > Add-ons menu, or by clicking on the Preferences item in the context menu of the extension in the Extension Manager.
Click here to get the addon – BlockSite . Install this to your Browser.