First login in your Gmail account than Go to google.com and search for what you want. You got the search results and you saw that domain which you don’t want to see again in your search results.
Click the browser’s back button from the website, which will give you the previous search results, but this time you can see a new link as shown in below image. Now you will be able to see “Block all Feature to this Website.
Manage your blocked sites by clicking on the above ‘Manage blocked sites’ link or log-in to google and accessing the URL. You can also block a website manually.
In this way you can block (remove) a website from appearing in your Google search results. You can block maximum of 500 sites and these blocked sites can be managed by clicking the gear button on the top-right corner of the search page.
Then click on Search Settings and then scroll down to see manage blocked sites.