We'll create fresh WordPress site with Set Bulk Post Categories installed. You have 20 minutes to test the plugin after that site we'll be deleted.
You can set & unset the categories of the posts in a single screen. Allows user to set the desired categories as well as unset the categories of all the posts in a bulk without editing the posts itself. Hierarchy of the respective category is shown in the light-grey color at the left side of the category which helps to understand if it is Parent or Child category. You can also Edit/Delete the posts at the same screen.