You can use toothpaste to wipe it off. If there is a lot of it and it is not easy to wipe off, you can use a stainless steel wire "cleaning ball" dipped in toothpaste and wipe it off. It can also be wiped off more easily. Don't use too much force, otherwise it will not cause damage to the porcelain glaze. After erasing, just rinse it with clean water.