The full rule is the following:
Apps that display user generated content must include a method for
filtering objectionable material, a mechanism for users to flag
offensive content, and the ability to block abusive users from the service
My app does feature user generated content. I have a feature that enables users to flag a post if they find it objectionable. I receive notifications in the database when this happens, and I personally judge if the content should be deleted or not. However, there is no feature that enables a user to block another user directly. There is no "following" or "friend requests" in my app, it is more like a communal forum where you read others content and can post your own content, but don't directly follow others.
my method of blocking others from the service is deleting user accounts and their associated posts from the database. Is what I have enough? I find the wording kind of ambiguous in the guidelines.