I recently noticed I have two copies of Illustrator on my computer. I am unable to delete the older one. Below is a screen shot from my control panel. I"m running WIndows 10 64bit.
1. When I try to delete from the control panel, I am broughtr to the Creative Cloud Desktop. There is only one option to delete Illustrator, and the newer version is deleted instead of the older one (see second screen shot).
2. When I reinstall via creative cloud desktop, the new version is installed but I am still left with the older version..
3. I've also tried uing the Creative Cloud Desktop Clean Up utility. Illustrator is not listed as on the computer, but even after refreshing and restarting, it is still listed in the Control Panel.
So as per your findings the application is not shown as installed by either the Creative Cloud Desktop app or the Creative Cloud Cleaner tool and hence you are not able to uninstall it. So here are the possibilities
The other possibilty may be that the program as uninstalled partially(check if the actual files are present in the Program Files folder). For this case you may reinstall the problematic version using Creative Cloud Desktop app and then uninstall it. Hopefully reinstalling the version will restore all the missing things and thereafter uninstallation would run properly. For steps on how to install a previous version see https://helpx.adobe.com/in/download-install/using/install-previous-version.html