Wood is a porous material into which any stain can set quite easily. If you have exhausted all other measures, bleach will remove most stains by penetrating deep into the wood and taking the colour out of the stain. However, bleaching wood will require refinishing the furniture or floor that you are treating. Still, one of the greatest benefits of using bleach to remove wood stains is that it will save you the cost of replacing your furniture or flooring.
Place plastic over the non-stained area of the wood, and tape into place. This will prevent you from accidentally bleaching any areas other than those which are stained.
Put on your gloves and protective eye wear.
Pour full-strength bleach onto the stain until the stain is well-saturated. Let sit for 15 minutes. Repeat if the stain is still visible.
Allow the bleach to dry on the wood once the stain is lifted.
Pour equal parts white vinegar and water into your bucket. Use the sponge the rinse the bleached areas of the wood. The vinegar will neutralise the bleach.
Let dry for 24 hours before sanding and refinishing the wood.
Use extreme caution when handling bleach.