Two solutions (one of which is terribly unacceptable).
Per the admin Leafo, they can remove the games you purchased from your account. Now, arguably you still have the ability to get the game (you still own it), however you have to re-add it in order to access/download it. ie. Go back to getting the spam. Not really a solution.
Alternately, setup a rule via your email provider or email client to automatically delete any email from postmaster@itch.io (or send it to spam, or other similar location). Not sure what other emails you might miss from itch, but at this point... Do you care?
I went with the latter. I want to be able to get the products I paid for.