How do I dismiss many multiples of the "Disk Not Ejected Properly" notification in macOS? Today I'm dealing with the following problem:



Is there some way I can get rid of these without spending my entire day clicking, short of Homer's Drinking Bird?

 

Note: This is not a duplicate of How do I clear All OS X notifications with 1 click?, because the notifications in my question aren't shown at all in the Notification Center, and thus the solution in that question doesn't work for this question.
I started killing processes with "Notification" in their name, and when I hit the one called "NotificationCenter" the smoke finally cleared:

killall NotificationCenter