I'm upgrading Elements and Premier but am concerned about memory occupied by old program versions. Adobe doesn't require removing old software versions but these versions occupy needed memory space. Is removing superceded Organizer, Photo and Premier versions a good practice? Will uninstalling these versions affect existing catalog data (albums, tags, backup)? Should these old software versions be uninstalled before installing the Elements upgrades?
Which version are you upgrading from? There is no real need to keep older versions present on your machine, but some folk do because of certain features that have been changed in newer versions. For example, the slideshow feature present for the past couple of versions is very different than earlier versions. Some users prefer the older version. Another example is the photomerge editor which now exists in Guided Edits.
It doesn't really matter whether you uninstall the older version before or after installing the newer one. But if you have sufficient disk space, I would wait until the newer version is up and running and you can judge for yourself whether it meets all of your needs.
One final point. If you have not yet purchased Elements 2020, you may want to wait a little longer. Based on past history a newer version usually comes out at this time of year.
Sorry, I forgot to answer your question about catalog tags etc. Everything will be converted over when you install your new version. When you first open the Organizer, you will be given the opportunity to convert your old catalog to the newer version. You should answer yes. Depending on the size of your catalog, the process can take a while. Be patient.
However, if you have a very old version (like Elements 9 and before), some extra steps may need to be taken to properly convert the catalog.
Thanks for the input. My upgrade is from 2019 for Photo and version 15 for Premier. My reason for upgrade is mostly the video enhancements. I have done Adobe upgrades previously and have encountered unexpected complications with deletions. My understanding is that once the Adobe Elements upgrade is complete and files converted, old versions have no practical purpose. Your suggestion is reasonable, do the upgrade and after some time to evaluate, remove the old versions.
And I am aware of Adobe's usual schedule of Elements updates in 4th quarter ... with Adobe's push for subscription based 'cloud' content, I wouldn't be surprised if Adobe slows updates or abandons the Elements product.