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.
Use J 38778
to remove the retainers from the wheelhouse and the splash shield.
Remove the wheelhouse splash shield from the wheelhouse.
Fig 1: Removing Wheelhouse Splash Shield From The Wheelhouse