Remove ink stains
Detergent solution, rust remover (oxalic acid or clover salt - both toxic!), Acetic acid (concentration of oxalic and acetic acid, each 5-10%).
Treat first with the mild detergent solution, then with a mixture of mild detergent solution and rust remover (oxalic acid), and third with a mixture of mild detergent solution and acetic acid.
Possibly. also cut a lemon, lightly squeeze the juice on the spot and absorb the ink. Then dab with water (use pulp).
But there are also special cleaning products to buy in the drugstore.