As per previous answer, the bezel is bonded to the display and I'm not sure it's possible to separate the two safely. I'm pretty sure doing so would affect the waterproofing.
However, you can buy a replacement bezel and LCD screen unit on line. Replacing the screen & bezel is easy… follow the first couple of steps in the ifixit guide “how to replace the battery”. Make sure the silicone seal is correctly placed when you reassemble it! Also, gently tighten the screws (about half a rotation each in turn) to ensure the bezel is seated totally flat to the body.
It'll cost you around £50 to £100 for the replacement bezel. Search on Google or Ebay.