This plug-in remove all comments from your current word press site. When Plug-in is active its remove all comments for all user. You can also remove comments from specific post type.
You have a option to removed comments only from posts or pages.
You can also remove from custom post type. For that you have to add code in your current theme`s function.php file.
Note: When you select “Yes” to “Do you want to remove all comments?” Its override all other option settings.