Any way to do this?

I was using Dallos River - Red Waterfall to cheese out easy XP/HL farming by combining all enemies and then abusing Steal Consciousness to kill enemies much higher level than my current party (Average level 30, killing enemies at level 300-400).

What I didn't realize though is that cheese killing Friday MK2 with the same Steal Consciousness strat meant that I can now randomly be sucked into an unwinnable fight (for my level) by doing random things, with one of them being combining units on Red Waterfall.

Any way to undo my unlocking of the dark world? It'd be a real pain in the ♥♥♥ to have to find somewhere else to farm. I only just unlocked Etna, the only other level with "Level Up 10%" is the Colosseum - Confession Room, and that place has silence everywhere.