WARNING: This page is about a different car, the 2020 Mazda CX-30. However, it is still accessible from the selected car via links, so may be relevant.
Remove the cap nuts.
Courtesy of MAZDA MOTORS CORP.
Remove the screws and cap nut.
Courtesy of MAZDA MOTORS CORP.
Partially peel back the rear splash shield.
Remove the rear mudguard in the direction of the arrow shown in the illustration.