If the ink hasn't dried, immediately blot the area with a clean cloth, turning the cloth as needed to prevent spreading the ink. After the damp ink is lifted, scrub the stain with small amount of whitening toothpaste. Allow the toothpaste to remain on the area for 15 minutes before cleaning the area.
Another option is to scrub the area with fresh lemon juice and salt. After spraying lemon juice onto the stain, sprinkle salt onto the lemon juice, and scrub the area with a cloth. Allow the juice to remain on the stain for five to 10 minutes before removing it with a clean cloth.
To treat difficult or dried ink stains, apply rubbing alcohol to the stain with a cotton ball, and place a paper towel over the area. After five minutes, remove the paper towel, and clean the area with a damp cloth. Rubbing alcohol can damage the wood's finish. Rinse the area with clean water immediately if damage begins to occur.
If the stain isn't removed with other methods, sand the wood with 80 or 100 grit sandpaper, and feather the sanded area out by using finer-grit sandpaper in the adjoining areas. Stain the wood to match the surrounding area and apply a topcoat after sanding.