Your data seems to be out of date

1) Sold records are from the county records, obtained through contracts with local data provider companies.

2) Syndicated listings come from all kinds of Realtor and Real Estate websites that specifically syndicate.  Of the over 700 MLS's only 2 of them Syndicate to sites like Zillow.

3) Agents and owners are allowed to "claim" properties and update any info they like (other than the address or amount sold for, or tax records... that takes a Zillow staff person to do).

4) There is a "report a problem" button under the edit pull down tab for anyone at all to mark discrepancies like the one you noticed so that it can be corrected.

No one says anything, and the syndication is still posted?  Then it still is fed to Zillow.  Zillow's system polls the syndicating sites every night.  They use a priority order on they syndication polling to try to get the more accurate info on listings and try to avoid the listings agents leave posted all over the internet for absolutely no good reason.  There is information about what website the syndication came from near the bottom of the home details page; and it is best to let the agent know they still have listings posted on a syndicating site that is posting to multiple sites, since removal from Zillow doesn't really remove the problem.

And yes, the home details page does state that it sold for $320k on 10/16/09 from the county records info.

By the way, Michael Luntz of ReMax still has it posted as for Sale on Propertypreviews.com, so that is the source of the problem.

Zillow readily admits that its Zestimates are only estimates based upon public records.  As to your current question, for sale listings are only as valid as someone makes them. If your home was listed on the site by a Realtor, then the Realtor must remove the listing.  You would need to contact them.  If a homeowner listed the home on Zillow, then you can remove it.  In the search area, put in the complete address of your home.  Yhen, click to claim your home.