Avodah Zarah 53 - Idol Nullification

A non-Jewish idol worshipper can nullify his own idol and that of his fellow. He needs to be an adult and of sound mind. A Jew cannot nullify the idol of a non-Jewish idol-worshipper. If a Jew comes into actual possession of an idol, it cannot be nullified but has to be hidden. That law is from the Torah, derived from the phrase " And place it in secret. "  However, the Sages have additionally prohibited any idol nullification by a Jew, since he might accidentally pick up it, thus acquiring it, and then his nullification would be invalid.

How does an idol-worshipper nullify an idol? If he cut off the tip of its ear, the tip of its nose, or the tip of finger, or flattened its face - he has nullified it. But if he spit before it, or urinated before it, or dragged it through the mud, or threw excrement at it - the idol is not nullified. If he sold it or gave it as a pledge for a loan, Rabbi Yehudah the Prince says that his nullification is effective, but the Sages say that it is not.

Art: John William Waterhouse - The Household Gods 1880