This is by Size15. It's posted on page 10 of that huge A2 Believer thread .
Get a thin flat-bladed screwdriver, or a thin blade and carefully insert it inbetween the two parts of the Z60 TailCap lanyard ring - you will find you can prise it apart to remove it... It can be 'snapped' together back on again if desired.
I hope this photo helps you see how the Z60 ring fits together?