Meant to be opened. I live dangerously and simply wiggle a finger into a corner to loosen and then open it slowly and gently with my hand , but you can also use a seam ripper or a small pair of cuticle scissors. Just hook the tip of the chosen utensil under a stitch and snip or pull slowly. Or, if this description makes you nervous, the next time you are in the boutique or at the dry cleaner. You can ask them to do it for you.
ETA: if you want the coat to maintain it’s perfect shape, some choose to leave the pockets closed, but I need all the pockets I can get.