This is a cream for acne problems of teenies, available without medical prescription. Its name Akneroxid in our country but it could have a different name where you live. The point is that the active ingredient is benzoyl peroxide.

There are two types: 50 mg/g and 100 mg/g it means 5% and 10%. 

You need 10% cream.

Apply the cream in thick layer to the spots and rest it for a day. If you can not see the ink the next day, wash it off  and the process is ending.

If you still see it as an ink, leave the cream for a further day. Wash it off.

For stubborn ink stains, the procedure must be repeated.