To reset your rating, you'll need to login with the player name you want to reset here:www.hardwoodgames.com
Once logged in, click "my profile" then go to the "game statistics" tab. Now scroll down to the game you want to reset your rating for and you'll find a button that says "reset".
You can also access this page by clicking on your name in the online lobby, and choosing "reset rating". For version 2 players it should take you right to the page, for older version games it will ask you for your player name and password.
Note: only your rating will reset, not the reset of your stats.