Many people say to use oven cleaner or lye, but the BEST way to to take it to an anodizing shop and have them strip the anodizing. Oven cleaner or lye can cause the aluminum to pit badly, doesnt strip evenly and will more than likely cause problems for your parts if/when you get them reanodized.
If you decide to strip the parts yourself, be sure to wear rubber gloves and eye protection.