How to Find Unused Images in WordPress

If you’ve had your WordPress website for more than a little while, there’s a good chance your media library contains images that aren’t being used – as you delete pages or posts from your site, these unused images get orphaned and serve no purpose other than to take up space on your web hosting account. Even if you have a web hosting plan with plenty of space, these unused files will increase the size of your backups and can get in the way as you sort through your uploads and media library to find what you need.
How to Find (and Remove) Unused Images in WordPress
WordPress lets you easily find unused photos in the media library (no plugin is required – so this will work with either self-hosted WordPress, or if you use WordPress.com). Here’s how:
Log into your WordPress admin dashboard.
From the menu, go to Media → Library
At the top of the screen you’ll see the search/filter bar and it probably looks like this:
Change the first dropdown to show “Unattached”
The grid showing images will now only show those that aren’t being used by any pages or posts on your WordPress site. You’re free to delete these, or keep them
Source: https://managewp.org/articles/13969/how-to-find-unused-images-in-wordpress

source https://williechiu40.wordpress.com/2016/12/06/how-to-find-unused-images-in-wordpress/