That collar provides the self-extraction mechanism. As you unwind the crank bolt (8mm Hex) it butts against the collar and forces crank off the BB axle. (SRAM used to use an 8mm hex with a 14mm hex on the collar – now they use a peg spanner for the collar)
Pop a slather of grease under the collar (to reduce friction whilst undoing 8mm hex) and re-fit it.
You’ll see the hex bolt has a shaped head that will match with the inside of the collar.
The arrow direction relates to the 8mm hex bolt – not the collar! As you undo the hex, it will “tighten” the collar due to the collar having a LH thread – if it was a RH thread on the collar that would unwind from the crank arm as you unwind the 8mm hex – make sense? (that’s where the grease comes in too – all the torque you are applying then goes into the removal of the arm rather than friction between the bolt head and the collar!)
If you’ve heard a crack you’ve probably broken the Loctite – but the cranks won’t come off until you refitted the collar. Nip the 8mm hex back up, refit the collar and try again……..
FWIW – they are bloody tight! I use a breaker bar, but an old pair of bars over the end of the 8mm allen key helps too. (until I got rid of the cranks………)
Hope that helps!
A