WARNING: This page is about a different car, the 2006 Subaru Outback and 2006 Subaru Legacy. However, it is still accessible from the selected car via links, so may be relevant.
Lift-up the vehicle.
Remove the bolts (A) and plastic nuts (B), and then remove the fuel tank protector.
Fig 1: Locating Bolts And Plastic Nuts Of Fuel Tank Protector