Banishment

Banish the Grimm Troupe. Instead of completing the ritual, after Grand Performance seek out Brumm (the troupe's accordion player) and help him extinguish the Nightmare Lantern, sending the troupe away for good. This removes the Grimmchild charm and gives you Carefree Melody in its place. Mutually exclusive with Ritual - you can't fight the Nightmare King on the same save, so do that on a second file.