Are you sure what you have is a tan? Since how many days do you have this problem? Or are you 'assuming' that it is a tan? Please visit an allopathic dermatologist and get yourself diagnosed. Chemical peels are used for specific conditions. They can be of help and sometimes don't work. But that depends on what condition you have. So visit a dermatologist for a good examination of your skin and diagnosis so that your treatment is smooth and gives you the best result.
Chemical treatment may be temporary. You need to improve your overall health. Use kunkumadi taila mixed with shatadhauta gruta for application. Use Saribadyasava 15ml with water twice daily after food. Medicines available at Ayurveda stores.