There is no listing in Programs and Features for the old versions to uninstall. These installs are on my (small) SSD. Can I safely just delete the folders?
Yes they can be removed to trash from your application folder on a Mac or uninstalled using the normal PC procedure. They are all available from the Adobe Product downloads if needed.
Register your product in your Adobe Account to keep your license keys safe and available for retrieval if needed in the future.