It is a freehub that only comes off by a hex bit. The solvent wash is the best method to free it up. The cog can be removed by prying the snap ring off and the cog will slip off, but not needed. Washing it with light oil will be your best bet. Looks like a lot of the BMX hubs I built and watched the kids race in the ABA and NBA. I hope the rest of the bike has the matching anodized parts. Post a Pic of the whole bike for us to enjoy. Smiles, MH