It is easy to access that speaker in that model. The speaker is mounted to the metal piece that surrounds it and the defroster vents just behind the windshield.
The metal piece is held in only by spring clips - carefully pry it up (I would start in the middle), work slowly so as not to bend the metal or damage the padded dashboard. It will pop off with a little patience. If your car has a sun sensor (small black round thing) disconnect the plug to that (if removing the metal piece completely). Then disconnect the plug to the speaker and you're done. You could remove the speaker itself but if your goal is to disable it you can just leave the plug disconnected.
Line the metal piece up with the spring clip retainers and press it into the dash. It takes a pretty firm push to fully seat it.