Is it permissible to cross out the faces of girls in school textbook pictures, or is that forbidden?

Drawing animate beings by hand is forbidden by the majority of scholars. As for photographing them with a camera, there is a difference of opinion among contemporary scholars, with the more preponderant view being permissibility. If the pictures are hand-drawn, then it is legislated to efface them, based on the saying of Ali ibn Abi Talib: "Shall I not send you on the mission that the Messenger of Allah, peace and blessings be upon him, sent me: that you leave no statue but you efface it, nor any elevated grave but you level it." And in another narration: "nor any image but you efface it." Effacement is achieved by obliterating the face.