it's a real pain in the ass to remove the inner ring ... outer ring was easy with the double side tape trick . but the inner is not easy to remove ... i try it to punch with a screwdriver .... real shit !!!
I had to remove mine a few weeks back, took me forever and when i did eventually get it out it had split so wouldn't go back in again. I used 2 allen keys and put them in opposite holes to turn it, it really is a pain in the ass though.
I had to soak with a penetrating oil for a wait and then i was able to get off, you did remove the small set screw or in some cases screws on under side.
Some have built a three pin jig to rotate it. I'd use a small punch, put it in one of the holes and side tap it around to get it started. The key to easier access next time is to use anti-seize when it goes back on.
i've put some penetrating oïl and let it go for the night ..... but my lens is cracked in the middle .. i hope i can buy the lens only ... real pain in the assss
you can also get someone to push in on the headlight itself while tapping the ring with a small pointed punch/hammer. remember; righty tighty lefty loosey