I added a custom recipe for starmetal ore; how do I remove the way iron turns into starmetal?

What do you mean datapack? I cannot find the data folder in the config file

Also I am in V1.12.2

Also I am in V1.12.2

Oh, I don't expected that. The datapack was added to vanilla in 1.13, so 1.12 cannot use that.
How about removing it using CraftTweaker? https://docs.blamejared.com/1.12/en/Mods/Astral_Sorcery/Transmutation

try datapack. the origional recipe is in astralsorcery\data\astralsorcery\recipes\block_transmutation\iron_starmetal.json.

ty