Tara, I just talked to Michael Dresdner, a well known finishing writer and expert. Neither he nor I have had to deal with this type of stain. My first take was oxalic acid, just based on the color of the stain; Michael's was that or lemon juice -- no guarantees. Dick mentioned two-part bleach, which is pretty certain to take all the stain color away. Either way, bleach first, then sand it, then tone it with some blend of dye stain to match the color, then topcoat. It's hard to tell from the photo, but it looks like it might be veneer, not solid teak. If so, do the minimum amount of sanding.
Ellis Walentine, Host