versions

Updating manually gives you a checkbox option to keep or remove previous versions.  If you allow CC to update apps automatically, you probably never see that option.  For that reason, I turn off automatic app updates from Preferences (gear icon) > Apps.

Owing to Adobe's version policy, pre-2019 versions are no longer available unless you kept them installed on your system.  There are times when older versions are desired to support a deprecated feature or 3rd party plugin.  When you're ready to uninstall older versions, do it from your CC Desktop App.

There is, or was, an option in the CC DTA when installing one UpGrade (Note the reference to UpGrade and the word One) to remove the older version that is currently installed.

That option was checked by default but if at anytime you unchecked that option the install routine leaves the older version.

If you do 2-3-whatever number of upGrades you can end up with all those older version installed.

If you do multiple upgrade installs at the same time, 
Update/Upgrade All", you never see that option to remove the older version.

https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html to remove programs