phphmyadmin-wordpress
If you are not using any plugin and don’t want to install one either to delete your Post Revisions which could take a lot space in case you have too many blog posts with revision, in this case you can delete all of the post revision at once by excecuting below query in your database using phpmyadmin, before you do make sure to back up database
DELETE FROM wp_posts WHERE post_type = "revision"; voila! you should have all of your post revision deleted by now!
