I was able to find the getSmeltingList(), but I cannot get it to call the remove method from the list. I have ran the following init method.
@EventHandler
public void init(FMLInitializationEvent event)
{
MinecraftForge.EVENT_BUS.register(this);
FurnaceRecipes.smelting().getSmeltingList().remove(Blocks.iron_ore);
GameRegistry.addSmelting(Blocks.coal_ore, new ItemStack(Items.coal, 1),0);
GameRegistry.addSmelting(Blocks.iron_ore, new ItemStack(Items.iron_ingot, 1),0);
GameRegistry.addSmelting(Blocks.gold_ore, new ItemStack(Items.gold_ingot, 1),0);
GameRegistry.addSmelting(Blocks.diamond_ore, new ItemStack(Items.diamond, 1),0);
GameRegistry.addSmelting(Blocks.redstone_ore, new ItemStack(Items.redstone, 4),0);
}