older versions on hard drive

It can if you specify it in your download options.

Most people like to keep older versions just in case the new one doesn't work right on their system.  Once you're certain you don't need the old one, you can manually unistall it from CC Desktop app or your operating system.

I've moved this from the Using the Community forum (which is the forum for issues using the forums) to the Download and Install forum.

Doesn't an update overwrite each app?

By @callmebrian

Only if the CC app settings are set to do that.

Can I delete the older versions (2021)?

By @callmebrian

Yes, but you may want to wait and be sure that the new versions work OK and that you don't need any of the old versions.

You may not be able to reinstall the old versions.