To version on computer - how to safely remove older?

Thanks for the replies. I deactivated the older version. This also deactivated the new version too. I then went to Control Panel and then uninstalled the old version. Then I started the newer version and had to login and supply the serial number for the new version (glad I saved it). The new program started up fine. 

The activation schemes have changed over the past year or so, so it seems like deactivating one version will deactivate all versions on the same device.  This is certainly the case with Creative Cloud apps.  If this is what happened to you, simply sign back in to Elements 2024 after you uninstall Elements 2023.   All you will probably need to do is confirm your correct account email, and activation should complete automatically.

Yes you are probably missing something.    Start 2023, the editor.   Log out of it- that deauthorizes it on that computer. 

I also asssume when you installed pse 2024 you imported your catalogues from pse2023 when prompted. 

Each version is it's own installation- it's virtually impossible to log out / deauthorize two versions  at once, with one exception that I am aware of:

If you have anything to do with adobe creative cloud and log out of that- you will log out of all adobe programs on your computer.   It happens to me If I log out, and log back in to the adobe creative cloud with my school (I'm a teacher) credentials.  When I log in with my school stuff I have access to all adobe apps.  I use the creative cloud interface quite a bit tas I subscribe to Photoshop-- which is the best $10.85 a month I spend. 

I've got about 12 versions of pse installed: I've never had any issues with any of them- as what you described.  

After you log out of pse 2023 It doesn't matter how you uninstall it-  for example:  I use Ccleaner to unisntall everything. 

If deleting a little over 4GB of  stuff is needed to save disk space it's probably time to think about getting a bigger hard drive.   When I get close to running out of space I literally just plug in another SSD- actually bought an expansion card so I can hard up to 4 more hard drives.