Plymman, this is very tricky and the risk of damaging your bezel is pretty high.
What you need is the bezel removal tools similar to Rolex 4 pronged type and also knows where the spring inside the bezel is located at. To do this, you need to remove the glass and then the insert.
I would suggest leaving this to a pro with proper knowledge to work on Omega bezel removal and with proper tools.
Do you really need to replace the bezel, or just the insert?
I believe the insert is easy (I did my UPO in a few minutes with a hair dryer, tweezers, and gorilla glue), but the entire bezel will probably require a watch smith.
It can just be the insert - the bezel is fine. I was planning to get a gen insert and case back as the dial is excellent its only really the insert and back that are the tells. However I think I made the wrong choice in buying blue (should have gone black) so I might not do this now, just move it on and get the black instead....