Certain professions such as mayor, sheriff, deputy and outlaw are all characters that could experience permanent death otherwise known as permadeath.
Permadeath happens when your character is executed by the law for a high crime or if you are a perm-able character and are killed through an admin approved assassination OR if you are a perm-able character, agree to partake in a duel and lose. If you are an average person and wish to kill off your existing character forever you may; either through a fight or perhaps just a farming accident that turns deadly. When your character dies and it is a permadeath you must submit your new character for whitelisting again.
On the permadeath of a second character, within the same season, you must sit out the rest of that season. If you perma that second character through choice or you are executed or killed again, your lives have run their course and you will have to wait to play and whitelist again. This is to prevent an overflow of people rolling the same sorts of characters over and over. Want to play nothing but murdering outlaw characters? You better get good at hiding and surviving in the wilderness.
See the Crime & Punishment page, ‘Assassinations’ section, for more information on perma-death.