How to unsubscribe from Apple Support Community

As your sign-in is also your Apple Account/Apple ID, you can't cancel the without all your Apple gear not working. Simply stop using the forums.

If you are getting bombarded with community emails, you can stop that by logging in one more time, clicking on you avatar in the upper right of any forum page

and selecting "Preferences" from the resulting drop-down:

When your Preferences open, scroll down until you see this section:

Uncheck every box, and you will no longer receive any more community messages.