On the Day of Atonement, what was done with the scapegoat?

Answer: It was sent into the wilderness

Aaron confessed Israel's sins over the live goat's head, and it was sent away into the wilderness carrying their iniquities.

“Then he is to lay both hands on the head of the live goat and confess over it all the iniquities and rebellious acts of the Israelites in regard to all their sins. He is to put them on the goat’s head and send it away into the wilderness by the hand of a man appointed for the task.”— Leviticus 16:21 (BSB)