It is a positive commandment to destroy, preferably by fire, false deities.
It is a positive commandment to destroy false deities, all their accessories, and everything that is made for their purposes, as [Deuteronomy 12:2] states: "You shall surely destroy all the places [where the gentiles... served their gods]" and, as [implied by Deuteronomy 7:5]: "Rather, what you should do to them is tear down their altars." Rambam, Hil. A"Z 7:1.
Most (all?) positive commandments have an accompanying blessing. I have not been able to locate a blessing for burning, say something like chick tract. Generally, I just burn them without a blessing. Is there a blessing for burning avodah zarah, and if not, why?