When you first install WordPress it creates a dummy post called “Hello world!”. The comments on this post are automatically turned on by default, even if site-wide comments are turned off.

Delete the “Hello world!” post
– Go to Posts -> All Posts
– Find the “Hello world!” post and delete it

To disallow comments completely, follow these steps:
– Go to Settings -> General
– Make sure “Anyone can register” is unchecked
– Save Changes

– Next go to Settings -> Discussion
– Uncheck “Allow people to post comments on new articles ”
– Then make sure the following options are checked:
– “Comment author must fill out name and email”
– “Users must be registered and logged in to comment”
– “Comment must be manually approved”
– “Comment author must have a previously approved comment”

Your site should now be immune to any new comments.