Before putting your Magento site live, you’ll probably want to clear out test data. Plenty of searches for Magento pull up older versions of the software when the database tables also differed. This is a new version of the script that deletes test data from Magento 1.5 and you can paste it all straight into phpmyadmin (after backing up your database first)
http://www.myscienceisbetter.info/delete-test-orders-in-magento-1-5-x.html