If you are using an Apple Mac computer, then follow the steps below to remove it.
Press Command, Option and Esc keys and this will bring Force Quit window. Select Safari and click Force Quit. This will close Safari.
Then hold down Shift key on your keyboard and open Safari. Then close that pop up and close that website. Then click on Safari menu and select Clear History and Website Data. On the dropdown next to Clear, select All History and click Clear History.
(If you see Reset Safari instead, click it and Reset Safari)
That will remove it.
If you are using an Apple iPad or iPhone, then follow the steps below to remove it. Press and hold down the Power button and Home button at the same time until it shows the Apple logo. When you see the Apple logo, release the buttons and let it boot.
Then without open Safari, go to Settings and tap Safari. Tap Clear History and Website Data. That will clear Safari.
Let me know if you have any difficulty.