remove … all the articles: Josiah removed detestable items related to pagan worship from the temple.
the fields of Kidron: The fields of the Kidron Valley were close to the Valley of Ben-Hinnom. In that valley, people once carried out ceremonies for the god Molech. These ceremonies involved burning children as sacrifices. Later, the Kidron Valley became a place where ashes and dead bodies were taken (Jeremiah 26:23).
Taking the ashes to Bethel, where Jeroboam set up one of his cult altars (1 Kings 12:28–29), would defile the site forever.