If you are experimenting with RSS feeds or your feeds get messed up somehow, you may want to purge the RSS feeds. The purgerss link is found on the Main Page under RSS Functions.
Once on the purgerss page, you simply enter the number of days back to purge the RSS entries and hit enter. NOTE: PHPList 2.10.2 (and possibly other versions) has a bug on this page--you must enter a negative number for the days to purge. For instance, to purge entries for 10 days back, enter -10, or to purge 30 days enter -30.