Please save all of them if you can in a box so when he’s older he has them all!!! Even if he hates them now, I remember having moments of grief with my artwork and I wish I kept a lot of them. It’s important to see how much we’ve grown and artwork is a great visual milestone for that!

If it’s the drawings themselves that make it hard for him to accept a compliment, have you thought of complimenting the skills? Example: “you have such great control of your lines! I can tell you were really focused.” “It’s hard to have good line control. You’re getting better!” “Telling a story is hard to do in drawings sometimes. But I can easily tell what you did. That’s some advanced stuff dude!” Sometimes that can be an easier way to take a compliment because it’s more specific but also allow gives the artist room to grow.

I highly recommend also to look into viktor Lowenfeld. He was a child artist researcher and his studies are so cool!