Each Clan member can leave their Clan whenever they want. When the Leader wants to leave the Clan they must appoint Clan member for the next Leader before leaving.
Each Clan member except for the Clan Leader can be kicked out from the Clan by authorized members. But if the Leader has a punishment by the Game Moderator for more than 14 days or has been inactive for more than 14 days (20 days if they have activated Vacation mode), the next Leader is chosen automatically by Experience. The Clan member with the highest Experience becomes the next Clan Leader.