How can I De-cheese my Mac and cheese. I think it's too thick. I think my béchamel screwed me.

Milk, as suggested. Or if it seems to gooey-cheesey, not just too thick, you could fold in a thinner bechamel without cheese.

If you put the bechamel on and baked it already it might be a loss but if you can thin it with broth or like Nan said more milk that is a best bet....maybe add a pitch of salt sometimes it helps with a heavy bechamel. Happy cooking!

try adding more milk to thin