The plug does "snap" in place so it will require some light force to remove. Try some tweezers or fine point long-nose pliers. You may also try to pry it out (gently) with something pointy, working one side at a time.
Be careful because you don't want to do any unnecessary damage to the housing, port or glass.
If you don't have the proper tools, consider going to your local shop and they may do it for a low fee.