The cape looks like it should snap right off. After that, use a rotary tool (Dremel, Blue Hawk, etc) to grind down the excess. Next, wet sand the shoulders and areas that the cape was actually glued to starting with 320 grit sandpaper and work your way to 600 grit to give it a nice smooth finish.
Are you re-painting the whole statue or just changing the red to blue? As far as the "exact color blue", I don't think there is such a thing, just as no two Hulk statues use the same color green. It's whatever your preference is. Personally I think a matte black with a metallic blue would look sweet!