If I forgot to plug in my Mac to the power and came back a couple of hours later, it may show "Disk Not Ejected Properly" notifications (two of them on Mojave).

But the notification display a "Show" and clicking on it has no effect. Clicking on the notification has no effect. So these two notifications are blocking all the view of other window content because they always stay on top of every other window. (they are blocking the tabs of Google Chrome)

How can they be removed? Or else I have to close most everything and restart the Mac, which is a pain just due to this bug.