how can i get the stain out of this ink

my friend colored on the other side with a pen i tried to get it off with a wash cloth and the ink bled through. this hat is my other friends hat so i don’t wanna be responsible for it getting messed up. any advice would be appreciated

my friend colored on the other side with a pen i tried to get it off with a wash cloth and the ink bled through. this hat is my other friends hat so i don’t wanna be responsible for it getting messed up. any advice would be appreciated