Sand the entire surface of the leather gently with a fine-grit sandpaper, applying steady pressure and working carefully to avoid wearing the leather too thin. This will remove the top layer of leather along with most of the spray-on color.
Dip a clean rag in denatured alcohol or lacquer thinner and vigorously scrub the surface of the leather. Use alcohol to remove alcohol-based dyes and thinner for any other type of dye. If you are unsure what type of dye was used, start with alcohol and remove any remaining dye with thinner. Use only a small amount of alcohol or thinner as too much could dry out and further damage the leather. Rinse the leather with warm water and a soft cloth.
Apply a thin coat of linseed oil to the leather using a soft cloth. The linseed oil will smooth the roughness from sanding the leather and restore moisture lost through cleaning with denatured alcohol and/or lacquer thinner. The oil will also a protect the leather from future damage.