From the NannyMUD documentation

LAST CHANGE

2000-12-08

COMMAND

NAME
        banish - Remove a name from possible use.


LOCATION
	Wizmod, module 'default'.

SYNTAX
	banish [-f] 

DESCRIPTION
	This command banishes the name, making it impossible for a
	player to have a character with this name. This is usually
	done on offensive names, and for characters that have behaved
	badly. The latter can only be done using the -f option, which
	is only available to the admin.