my sunroof has that too and i hate it. youre not gonna get it off. its ceramic thats baked on. i was thinking of tinting my sunroof, but there is a specific glue to use for that. i heard of people sanding it down with fine sandpaper, but it usually turns the glass hazey.
I just went to my local windshield repair shop and ordered a new piece of safety glass cut and replaced it ...