“demolish.” God has no tolerance for idols. They are harmful in many different ways. They are to be destroyed. See commentary on Deuteronomy 7:5.
“sacred standing-stones.” It was a common practice, especially among the Canaanite cultures, to take stones, natural or with some shaping, and set them upright as a part of the recognition and worship of a god, or to set them up as a cultic memorial of some event. God commanded Israel to destroy those stones, but given all the ones that have been uncovered by archaeologists, apparently often that did not happen. [For more on standing-stones, see commentary on Gen. 28:18. For more on idols being harmful, see commentary on Deuteronomy 7:5].