The ephors were a collective of five Spartan citizens who shared power in Lakonia with the two Kings of Sparta. In effect, they acted as overseers for the two kings and had the power to dethrone and exile them, if need be.
Exactly that happened around 425 BCE, when King Pausanias was revealed to be an agent of the Cult of Kosmos, and was exiled from the polis.[1]