Also, you can't abandon quests tied to the main story. Those are the ones where the icon looks like it's on fire.

Just switch to another class. At some point you will want CNJ leveled anyway. Just consider it partially out of the way. And I don't consider having Cure, Raise nor Protect worthless cross class skills. All my other classes have Cure equipped and I use it for emergency heals when I solo. I also often have Raise equipped so I can Raise dead PCs I come across. I've even had to toss out a couple emergency Cures in low level dungeons. It comes in handy. You can never have too many skills at your disposal in this game.