To unsubscribe from the push notifications th easiest way is to clear the cache from your browser.
Clear your browser cache by doing the following: 1. Open your browser 2. Go to settings 3. Find the option to clear your browser history/data 4. Delete all or recent data.
After you've deleted your browser cache, you won't receive any more push notifications from the websites you've opted-in. If you ever decide to receive push notifications again, simply go to the website you wish to receive push notifications from.