Albert Barnes Commentary 2 Chronicles 30:14

"And they arose and took away the altars that were in Jerusalem, and all the altars for incense took they away, and cast them into the brook Kidron." — 2 Chronicles 30:14 (ASV)

The continuance of the idolatrous altars until this time shows that Hezekiah had been more eager to build than to destroy, and to establish the worship of Yahweh than to root out idolatry. Now, however, that the more important work was done—the temple reopened and the daily service restored—attention could be turned to the secondary task of removing from the city all traces of the recent apostasy.