Pen ink stains can be frustrating and seemingly permanent, but there are several effective methods to remove them from paper. The specific method that works best will depend on the type of ink and the age of the stain.
One common method is to use rubbing alcohol. Apply a small amount of rubbing alcohol to a cotton ball or swab and gently dab it onto the stain. Allow the alcohol to sit for a few minutes, then blot it up with a clean cloth. This method is most effective on fresh stains.