If you have been trying to remove coffee, wine, or other stains for years, it is probably better to go to the dentist for a professional whitening treatment.
However, if you want to remove superficial stains in a fairly non-abrasive way gently, charcoal powder or charcoal toothpaste may be enough.
Many reviewers found that activated charcoal outperformed their regular stain removal toothpaste: again, these claims are subjective and have not been scientifically proven.