Hi Orlanda,
The system files that were backed up are contained in a 'backup' sub-directory of the program you did the installation for. So for the Inventory upgrade, these system files will be in \softrak\icwin\backup. These backup files will not affect data backups, but they will affect the size of system backups.
If you are content that the upgrade completed successfully, it is safe to remove the contents of the backup directory.