Now, we understand how mortifying it'd be if you really were caught watching Bosch, so we dug deeper -- and we found one of the most futile Amazon help threads in existence. Turns out no one knows how to do a full reset, although if you have a Samsung smart TV, you can sometimes get this to work just by deleting items from the list. If anyone figures out a more reliable technique, please go to this desperate, desperate thread and help these guys out (and us, really).
Another thing to be aware of: Amazon is the biggest snitch imaginable and sends emails to the account holder asking how you liked something after you watch it. Unfortunately, you can't disable these either, but if you delete your watch history right away, that should do the trick.