The release note that was made for SmarterStats 8.4.5010 was a specific issue where logs that SmarterStats pulled through FTP were not being properly deleted within the SmarterStats folder itself. The software pulls the logs locally and processes the data, which then should have been deleted. It was recognized that in fact the logs weren't getting deleted, which is what this release note is addressing.
SmarterStats does not currently have the functionality to delete actual logs from the FTP server. If your looking to delete the raw IIS log file from the FTP location that SmarterStats is pulling from you would need to handle this through a manual process outside of SmarterStats.
If your still seeing an issue where older FTP logs are stored in the SmarterLogs FTP folders past a day, then this would be something that we need to take a look into further.