I don't know of any way for individual users to filter them out of the "View New Posts" or "Today's Active Topics" page. I can filter them out of that page altogether by password-protecting both News Feeds forums or by sending all Potter news feeds to the currently password-protected forum.
But I'm not yet inclined to do either until September or October. I have a reason for enabling those RSS feeds. Bottom-line: I ask for your patience.
Nonetheless, I appreciate you letting us know of your concern. I've been pruning the old reports out of those forums, so what I (and my co-mods) can do for now is to prune them more frequently so that fewer feeds show up in those "new topics" pages.
EDIT mid-Aug 2008: We've fixed this by doing the things in the first paragraph ahead of schedule.