I have yellow bright yellow teeth that are crooked but i am going to get braces. how do i remove the stains?

Before or After: It depends on what types of stains the yellow stains are made of. If it is a film of bacteria, it will be mostly removed when you get brackets, as all outer surfaces of teeth will be cleaned first. If the "stain" is actually decay, it is treated first. If the stain is within the enamel, it may be more practical to treat it after completing braces. Ask your doctor which case yours fall in.

Intrinsic/extrinsic : Stains can be on the surface of your teeth or within the tooth enamel due to development or mineralization and demineralization processes. Surface stains can be cleaned away. Intrinsic stains can respond well to bleaching agents. Also as our teeth are subjected to trauma...Including normal chewing and use they can darken from within due to a thickening of the dentin as the nerve recedes.