Okay, it has been confirmed, you need to lose the wristlet(s) in order to back out of the quest before completion. Thanks Synestr and SE's GM team.

Greetings,

Thank you for contacting FINAL FANTASY XIV: A Realm Reborn in-game support.

In order to cancel the quest for Eternal Bond, you need to give the wristlet back to the Sanctum Acolyte NPC next to the Sanctum Outfitter and Claribel in the Sanctum of the Twelve.

We thank you very much for your GM Call and we wish you a very nice day.

Regards,

FINAL FANTASY XIV: A Realm Reborn Game Master team