WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
Open the liftgate.
Remove the bolt that retains the child restraint tether anchor to the floor panel.
Fig 1: Locating Rear Anchors
Courtesy of GENERAL MOTORS CORP.
Remove the child restraint tether anchor from the floor panel.