Help for /depermit

Usage:  /depermit others|user[,user,...] discussion[,discussion,...]

On occasion there will be users you wish to remove forcibly from one of the 
discussions you are moderating. The /depermit command is your mechanism to 
exercise that ability. Once depermitted, a user is removed from the discussion 
and can no longer see it in their /what list.

To depermit a specific set of users, use "/depermit user1,user2 discussion". To 
make a discussion private to all users except those specifically permitted use 
"/depermit others discussion".

(see also: permit, discussions, what, clear, appoint, unappoint, moderators)