furnace.removeRecipe(<item:minecraft:iron_ingot>);
furnace.removeRecipe(<tag:items:forge:ingots/silver>);
furnace.removeRecipe(<tag:items:forge:ingots/tin>);
furnace.removeRecipe(<tag:items:forge:ingots/uranium>);
furnace.removeRecipe(<tag:items:forge:ingots/nickel>);
furnace.removeRecipe(<tag:items:forge:ingots/copper>);
furnace.removeRecipe(<tag:items:forge:ingots/zinc>);
furnace.removeRecipe(<tag:items:forge:ingots/iron>);