Notifications from a website I don't visit on my desktop

Solution 1:

If you are using Google Chrome, then go to

chrome://settings/content/notifications?search=notification

and block unwanted notifications.

For Firefox ESR go to Preferences → Content or

about:preferences#content

then click Choose

and switch unwanted site to Block then Save Changes.

For Firefox Quantum go to Preferences → Privacy & Security then near Notifications click Preferences button and manage them