Hi, with the 2020 edition you are able to delete the 2018 edition, but afterwards you would need to install 2020 again as the 2018 install will delete the stock images. I know this is not good, but going forward the changes we have made will mean … in 2021 you will be able to uninstall the 2020 version with no effect on the 2021.
regarding the backup files, we would never delete the backup folder during an uninstall as it may contain data the user still needs