John Gill Commentary 2 Chronicles 33:15

"And he took away the foreign gods, and the idol out of the house of Jehovah, and all the altars that he had built in the mount of the house of Jehovah, and in Jerusalem, and cast them out of the city." — 2 Chronicles 33:15 (ASV)

And he took away the strange gods, and the idol out of the house of the Lord Which he had set there, (2 Chronicles 33:7)

and all the altars that he had built in the mount of the house of the Lord, and in Jerusalem ; see (2 Chronicles 33:4 2 Chronicles 33:5) ,

and cast them out of the city ; perhaps into the brook Kidron; all this he did to show the sincerity of his repentance for his idolatry, and his abhorrence of it.