The newly updated App Store Review Guideline 5.1.1(v) states that:
... If your app supports account creation, you must also offer account deletion within the app. ...
The guideline leaves two important questions open:
What does it mean to offer the account deletion?
Is it enough to point the user to the website, email, ... or does the deletion need to be completed within the app?
Does Apple expect a simple account deletion (in the sense of inactivation) or a full delete-all-my-data request?
Is there a statement from Apple which specifies these details or has someone already receive an app rejection for it?