If it's sagging, you can just pull the material down and rip it out. Parts stores sell little screw in pins to hold it up. Looks like down stuffed tuck and roll, then.
Bare, the fiberglass backer board is ugly yellow and nasty looking (every time I glance at it.) Kits are available on the internet, about $30, come with a can of spray glue, fabric enough for liner and visors, and some advice. You get to remove all the plastic trim and do the work. Good springtime mod - not so fun in the winter. It looks like it could take more time for removal and installation than covering with fabric. The visors snap fit together.
Going bare metal is frigid in winter and loud year round. Think twice about it.