Is repentance for drawing animate beings sufficient, or is it obligatory to inform those who were given the drawings to efface them?

It is not permissible to draw images of living beings due to the severe warnings mentioned regarding this. You have done well by repenting and refraining from drawing.

You should explain to your two friends the impermissibility of drawing and the necessity of effacing images, based on the saying of Ali ibn Abi Talib: "Do not leave any statue but you efface it, nor any raised grave but you level it." In another narration: "Nor any image but you efface it."

If they respond positively, then praise be to Allah. If they do not respond, then there is no blame upon you. For the one who repents after having engaged in the cause of sin has fulfilled their obligation. "And if a servant does well in what they are capable of, then what they are not capable of falls away from them."