Minecraft Forge 1.7.10-10.13.2.1236 - Method to remove all furnace recipes that result in the specified ItemStack.

RecipeRemoverFurnaceSnippet.java

public static void removeFurnaceRecipe (ItemStack resultItem)
{
	Map<ItemStack, ItemStack> recipes = FurnaceRecipes.smelting().getSmeltingList();
	for (Iterator<Map.Entry<ItemStack,ItemStack>> entries = recipes.entrySet().iterator(); entries.hasNext(); ){
		Map.Entry<ItemStack,ItemStack> entry = entries.next();
		ItemStack result = entry.getValue();
		if (ItemStack.areItemStacksEqual(result, resultItem)){ // If the output matches the specified ItemStack,
			entries.remove(); // Remove the recipe
		}
	}
}