JeraldR, thanks for the quick response.  

These folders don't contain my company data files.  They appear to be folders left over from previous installations ("possibly" those years where I had to have Customer Support get involved and they did a backup folder before doing whatever steps that they did).

My data files are stored elsewhere and I purge those routinely (rather than the auto keep of the last 5 backups).

Please see my "new" screenshot which shows the typical content of one of the folder (e.g., the "Quickbooks 2021.old" folder contents as an example).

I am wondering which should be kept and which could possibly be deleted. 

The "QuickBooks" titled folder has file today's date (I opened QB today to test what files where were affected) for the "QBINSTANCEFINDER17.INI" file and the "qbsdklog.txt" file.  The rest of the files in that folder remain with older "Date Modified" dates.

**ALSO**...

The "QuickBooks2024" titled folder has file today's date (again, I opened QB today to test what files where were affected) for the "qbw.ini" file, the "wpr.ini", and the "qbbackup.sys" file.  The rest of the files in that folder remain with older "Date Modified" dates.  "QBPRINT.QBP" has a 04/28/2025 "Date Modified" date and that may be the last day that I printed something from within QB.  Also, the "Components" folder has changes to "Date Modified" for today to its "Messages", "TI", "QBUpdate" folders and files under each of those folders.  "WBUpdateCache" and "DataProtect" last had their "Data Modified" folder changed on 04/28/2025.

This "implies" to me that I MUST keep the folders "QuickBooks" and "QuickBooks2024" and, "perhaps", the other folders "QuickBooksYYYY" folders in the first screenshot can be deleted (after backing up, of course).

Further insight from you and others would be helpful.  Thanks again.