I am developing a custom modpack and I want to edit some recipes, however when I tried removing the recipes for hellshelf and seashelf nothing happens, I searched on this repo and didn't found JSONs for their recipes, I tried with all other shelfs and they can be edited except the hellshelf and seashelf.

Those use a slightly weird™ code recipe subsystem which hasn't been phased out yet. You can change their recipes by adding a new recipe with the same recipe ID.

Oh thanks, I never though it was possible.