The first important thing to understand is that SpyFu is not tracking your domain directly. We only track Google itself. So Google is tracking you and SpyFu is tracking Google on some keywords that you rank on.
As long as you continue to rank on Google, SpyFu will keep automatically tracking your domain as well. If this is content that you would rather not have indexed by Google altogether, update your robots.txt file or contact your web master to get search engines to stop indexing the pages of concern. Then SpyFu will also stop tracking those pages within a month or two as well.
So finally, the answer to the original question “Would you please stop tracking my site?” is yes. BUT we aren’t going to take any action on our side. As soon as we don’t find your site on Google everything should take care of itself. There will still be a page for your domain on SpyFu but with no data on it.