Dip a clean cloth in leather deglazer or acetone, and wring out the excess product. Wear rubber gloves to protect your hands from irritation.
Rub the deglazer or acetone directly onto the leather piece.
Wipe off the deglazer with a clean cloth to remove the top finish coat. Allow to dry.
Rotate to a clean section of the cloth or use a new cloth as the old one gets dirty.
Mix a solution of oxalic acid, a type of leather and wood bleach, with water to create a bleaching solution to dye the leather. Oxalic acid is commonly used to clean leather; follow the mixing directions for cleaning, but add more oxalic acid as desired to achieve a greater lightening effect.
Rub the solution onto the leather with a clean cloth. Let it dry to observe the results, and then repeat the process, adding more oxalic acid to the water if greater results are desired.
Soak the leather in the solution in 10-minute increments, allowing it to dry in between soaks for observation, until desired results are achieved. Try this step at your own risk and only if rubbing on the solution didn't produce sufficient results.
Color the leather with a leather dye, if desired. There are brush-on and dip-style dyes made specifically for leather.