I've got dozens of files pertaining to LR5.6 and 5.7 that I want to delete. What is the best way to delete ALL the files and registry entries associated with these versions without doing harm to my LR6 installation? Thanks!
If you still have older versions of the program installed you can simply uninstall them using the standard uninstall process used by your operating system. Lightroom 6 creates new versions of your catalog(s). If you know how to identify which ones you are using now, all of the old catalogs can be deleted. When Lightroom 6 is installed it creates a new copy of your previous catalog. The Lightroom 6 installation is completely independent, and does not rely on any program files from the previous versions. Lightroom 6 will continue to utilize the previews folder from the previous version as well as any smart previews that you have generated. So all you need to do is uninstall the older versions of Lightroom and then delete the older versions of the catalog files you have been using. It might be a good idea to retain one backup, probably the most recent, just in case you have a catalog problem in the future.
Thanks very much, Jim, for your prompt and helpful response!! Made my day!