Floor duct

WARNING: This page is about a different car, the 2003 Nissan Altima. However, it is still accessible from the selected car via links, so may be relevant.

Remove the carpet. Refer to "FLOOR TRIM "
Release foam tape and slide floor duct rearward to release from clips.

Fig 1: Releasing Foam Tape And Slide Floor Duct
Courtesy of NISSAN MOTOR CO., U.S.A.