leave the apple community

Apple Community is the series of user to user support forums, like this one. The easiest way is to just stop posting here. Also if you click on your avatar at the top right and go to Preferences you can set them all to not send you any email. Alternatively you can send an email to mailto:communityaccounts@apple.com However, I don't think that any posts you have made will be deleted because then any threads in which you participated would start falling apart and/or become meaningless. Read Apple Support Communities Use Agreement - Apple Community

If you mean close an entire Apple account, read —> How to delete your Apple Account - Apple Support

Carefully and thoroughly read that article for information about what happens when you delete your Apple ID account. For example:

"Make sure that you sign out of all your devices to avoid issues with apps that use your Apple ID account or iCloud. After your account is deleted, you can't sign out of iCloud or turn off Find My iPhone Activation Lock on your devices. If you forget to sign out, you might not be able to use your device when your account is deleted."