Iconoclasm
Iconoclasm is a belief that people should reject religious images (like icons or monuments) by destroying or avoiding them. This is the opposite of idolatry, the worship of icons. Iconoclasm happens during important political or religious changes. It is generally distinct from destruction by foreigners, for example by Spanish conquistadors in America.  The term does not generally include the specific destruction of images of a ruler after his death or overthrow (damnatio memoriae), for example Akhenaten in Ancient Egypt.