Usage: SECURITY NONICK [<command>] [<nick>]

These commands control the list of nicknames that users are prohibited from using. Network operators can still switch to these nicks. These prohibited nicknames stay on your server until deleted.

ADD - Add a prohibited nickname.
DEL - Delete a prohibited nickname.
LIST - List all prohibited nicknames.

/as help security nonick <topic>

There are some pre-set prohibited nicknames on every ConferenceRoom server. They are there to ban a list of nicknames that are commonly used in various chat places as the nicknames for services or administration. On networks that do not ban them, sometimes users will switch to these nicks and try to harm other users who recognize them as services or official nicknames.