WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
Open the hood.
Fig 1: Removing/Installing Radiator Air Baffle & Deflector
Courtesy of GENERAL MOTORS CORP.
Remove the retainers from the upper air deflector.