blotting out characters with ink; inking out text
Refers to the act of covering written characters with ink to make them unreadable, often for censorship or correction.
They released the confidential document after blotting out some parts with ink.
Compound of 墨 (sumi, 'ink') and 消し (keshi, 'erasing'), from the verb 消す (kesu, 'to erase').