This extension hide web pages for your request, you can manage blocked website any time through the extension.
Distracting pages blocker is a free extension that made to help you easily block your distracting pages to increase your productivity.
just install it and when you see a page that distract your concentration just add it to your blocked list.
you can always remove the blocked site easily in one click in the extension.
If you remove the extension all the blocked sites will return to be as usual.