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.