Use the Hackathon EAV cleaner module for this. After installation you can use the command eav:media:remove-unused

Also you can do it by installing the module below and running these commands.

composer require ekouk/imagecleaner “dev-master”
bin/magento setup:upgrade
bin/magento setup:di:compile
bin/magento cache:flush

Run in check only mode which will report the number and size in Mb of unused images.

bin/magento ekouk:cleanimages
Then run this command to delete the files.

bin/magento ekouk:cleanimages -d

Written by Al Mahbub Khan Full-Stack Developer & Adobe Certified Magento Developer

Full-stack developer at Scylla Technologies (USA), working remotely from Bangladesh. Adobe Certified Magento Developer.

How to Delete Unused Images from Your Magento Media Folder