WARNING: This page is about a different car, the 2006 Pontiac Torrent and 2006 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: View Of License Plate Lamp Assembly & Screws
Courtesy of GENERAL MOTORS CORP.
Remove the screws (2) attaching the rear license plate lamp assembly to the rear license plate lamp bezel.
Lower the license plate lamp assembly (1) from the bezel.