You can try to using baking soda to see if it helps whiten your teeth. Or buy some over the counter products to use. The best way is to talk to your dentist and see what they recommend for the best results.
You can get your teeth bleached professionally by a dentist. Otherwise you can try natural remedies such as rubbing lemon over your teeth before you go to bed. This should lift some stains from the teeth.
The best way to get rid of any tooth stain is by having your teeth cleaned by a professional. Not all stains can be removed, but many of them actually can be. Check with your dentist and look into a good cleaner.