I colored my hair and the red is too intense (not natural). I want to darken the color to auburn. What can I do and how soon?

There is a product called "Color Oops" that supposedly removes the accidental coloring. You should wait at least 6 weeks before doing anything else chemically to it. However, there are some very nice Henna dyes that you can use without doing much damage, but I still think you should wait a bit.