C. F. Keil and Franz Delitzsch on 2 Chronicles 31:1

2Ch 31:1 Destruction of the idols and the altars of the high places. Provisions for the ordering and maintenance of the temple worship, and the attendants upon it. - 2Ch 31:1. At the conclusion of the festival, all the Israelites who had been present at the feast (הנּמצאים כּל־שׂראל to be understood as in 2Ch 30:21) went into the cities of Judah, and destroyed all the idols, high places, and altars not only in Judah and Benjamin (the southern kingdom), but also in Ephraim and Manasseh (the domain of the ten tribes), utterly (עד־לככּה, cf. 2Ch 24:10), and only then returned each to his home; cf. 2Ki 18:4.