OH! I should have looked this up first. Yes, you can:
https://developer.roku.com/dev/landing
Sign in with your email address you used to register. If you don't know your password, just click "Forgot password" link, change/set your password, then sign in and visit the URL above.
Once you're in, click the link that says "Email preferences" near the bottom of the screen, select "Unsubscribe from all" and click "Save preferences." If you're lucky, that will remove you from the list.
I'm curious if that works for you!
