The answer to this question depends on whether or not the metal surface is painted. If your fireplace is made out of unpainted metal, it's possible to use an ordinary metal cleaner on it. Though, these products can be somewhat abrasive. So, it's important to not use them on a fireplace that's made out of anything else. Check the label of any metal cleaner that you're using to ensure that it is compatible with a painted surface, if your electric fireplace is painted. If it isn't, you'll still need to make sure that the product you choose is compatible with the type of metal that your fireplace is made out of.