Where is the backup folder located? Can I remove it?
Your original images are saved in a backup folder located on your server at: /wp-content/uploads/ShortpixelBackups/
You can remove the backup folder at any moment but in our opinion it is best to keep a local copy of the backup folder and its files. Just use an FTP client (please contact your hosting provider to help you with this) to copy all the backup files&folders locally.