Delete Duplicate Posts is a plugin for WordPress that does exactly what the name says. You can delete posts, pages and other Custom Post Types enabled on your website.
Demo: https://cleverplugins.com/delete-duplicate-posts/
CommentPress is a small but powerful plugin for wordpress that allows you to insert, edit and delete commentsfast and easy.
Demo: https://codecanyon.net/item/commentpress-ajax-comments-insert-edit-and-delete-comments-for-wp/4542951