Sure they can. Just bring up the Task Manger and close the Browsers.
And, if you happen to be running Microsoft Edge, you can shut down
just the offending tab, instead of the entire browser. When you open
the Task Manager (Ctrl+Shift+Esc), double-click on Microsoft Edge
and you'll see, among other things, an entry for each open tab. The
one you want to close is usually called Microsoft Support. Right-click
on it and choose End Task. Sometimes it will open up again very
quickly. If it does, just keep closing it until it stops opening, usually
only once or twice.
Unfortunately, this doesn't work for Firefox. When you double-click on
Firefox, it only shows an entry for each open window and not the tabs.
I haven't yet tested Chrome or IE.