This article explains that commissioners have the final say in private fantasy leagues and that Yahoo! will not get involved.  This article also has a link to the Manager Rating article.

In order to allow the independent features that make private leagues fun for all that participate, Yahoo! needs to remain apart from the day-to-day operations of fantasy leagues. Unfortunately, we can't remove teams from private leagues or act as intermediary between manager and commissioner.

Please use your league's message board or email your commissioner to resolve disputes if you have not already done so.

Based on customer feedback we have added a Manager Rating system on to our fantasy games. This will enable managers to rate (positive, neutral, or negative) the other members of their league, including the commissioner. Once this rating data is made public, managers will be able to see a commissioner's rating prior to joining their league. Commissioners who do not run their leagues fairly will receive negative ratings and managers will know not to join those leagues. Commissioners who run their leagues fairly will receive positive rankings and managers can feel confident joining those leagues.

Please note that the manager rating data will be collected for an undetermined amount of time before we add the ratings to fantasy profiles. The reason we are not publishing the data initially is we need to make sure we have enough data to provide accurate ratings prior to making them publicly available. The new manager rating system is available in all of the full fantasy games via the "Managers" tab.

While commissioners have full jurisdiction over the private leagues they create, Yahoo! acts as commissioner in all public leagues. We encourage managers to try our public league offerings as they can be assured that our Fair Play and Sportsmanship guidelines will be enforced in those formats.

PLEASE NOTE: Once a manager rating has been submitted, it CANNOT be undone. Also, you are allowed only one rating on a manager per league.