If it is aluminum, it is not blued, not possible, as bluing in and of itself is a controlled rust (rust being iron oxide), and since alum contains no iron, hence no bluing.
Depending on the age, if it is in fact aluminum, it is either anodized, or if it was made in the last couple years, it'll be powder coated.
Either way, the only way to remove it will probably be abrasively. At which point, you'll have a bare aluminum piece, which after time, will loose its polish/luster as it builds a layer of tough aluminum oxide, unless you put some sort of protective sealant on it (it can also be clear anodized).