WARNING: This page is about a different car, the 2003 GMC Safari and 2003 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
Remove the retaining screws from the upper garnish molding.
Use J 38778
in order to release the molding retainers.
Fig 1: Removing Retaining Screws From Upper Garnish Molding