How can I delete all featured images

Have areda of this:

https://wordpress.stackexchange.com/questions/43320/query-to-delete-all-featured-images-and-remove-post-meta

Thank you. I came across that post, however I am not 100% tech savy. I am not sure if I should download it as a “.php” file and upload it as a plugin. Do I need to modify the file?

Specifically this line:

A MYSQL Query cannot delete the files themselves. You will have to use wp_delete_attachment(). The following is a proof-of-concept for you to alter how you please. The featured image is stored in postmeta as _thumbnail_id. wp_delete_attachment() does the rest for you.

<?php
/*
Plugin Name: Delete All Featured Images
Description: Delete all featured images by visiting /?delete-featured-images=1
Version: 0.1
Author: Brian Fegter
Author URI: https://coderrr.com
License: GPL3v2
*/

# USAGE: visit https://yourdomain.com/?delete-featured-images=1

Thanks

sorry I meant this:

# USAGE: visit https://yourdomain.com/?delete-featured-images=1