Doing an R&R on the rear bumper on a 2006 CHEV Sub C1500 V8 5.3L

1. How do you remove the round retainer ring on the back of the bumper, that holds the spare tire mechanism/key lock in place? Everything else is straight forward but the ring is a bit flimsy and I don't want to damage it while trying to figure it out.

2. Do I need to disconnect the battery to prevent the bumper removal from activating the air bags, or will this not cause any problems with the SRS system?

Thanks, LCS