2 Kings 11:18
And all the people of the land went into the house of Baal, and brake it down; his altars and his images brake they in pieces thoroughly, and slew Mattan the priest of Baal before the altars. And the priest appointed officers over the house of the LORD.
Athaliah was the last of the house of Ahab, and her death ended the terrible evil that had come through alliance with Jezebel and continued until the last of his descendants was destroyed. Even in Judah, where the worship of the true God had never been formally set aside, she had succeeded in seducing many into Baal worship. The destruction of that worship came immediately after the impenitent queen, Jezebel's daughter, was executed, ending her influence. Then all the people of the land went and thoroughly broke down the house or temple of Baal with its altars and images, breaking them in pieces, and killed Mattan the priest of Baal before the altars. This removal of Baal worship marked the beginning of a reformation in Judah.