Charles Spurgeon Commentary 2 Chronicles 33:16

"And he built up the altar of Jehovah, and offered thereon sacrifices of peace-offerings and of thanksgiving, and commanded Judah to serve Jehovah, the God of Israel." — 2 Chronicles 33:16 (ASV)

And the idol out of the house of the LORD, and all the altars that he had built in the mount of the house of the LORD, and in Jerusalem, and cast them out of the city.

Sins which were before so pleasing to him are now abominations in his sight, and he flings them over the city wall like unclean things. In the very valley of the son of Hinnom where he had dedicated his sons to idols he now consumes his idol gods as foul and offensive things, to be cast away with all the refuse of the city.

And he repaired the altar of the LORD, and sacrificed thereon peace offerings and thank offerings, and commanded Judah to serve the LORD God of Israel. (2 Chronicles 33:16)

It was not possible for him to undo all the evil which he had committed, as he soon found out.

And he took away the strange gods,.

When grace comes into any man's heart, there is sure to be a change in his action. Manasseh "took away the strange gods,".