I am not a finish expert but I do a lot of woodwork and of course that does entail finishing the resulting projects.
There are products such as lacquer thinner, acetone, and wood bleaches available at your nearby hardware or paint store that might be able to remove the ink stain. The downside of those is you do not want to use them inside because the fumes can be hazardous to your health in a variety of different ways and there is a strong possibility they might strip off all of the finish as well as the stain.
I would try using denatured alcohol (I like to use the alcohol swabs or "prep pads" for this kind of work) to soften and remove as much of the stain as possible and after that has dried thoroughly (it shouldn't take long) soak the remainder using paper towels wet in a chlorine bleach solution laid on the desktop to bleach out any remaining ink color. CAUTION: Use protective gloves, clothing, and protection for your floors and be sure there is plenty of ventilation.
