Hiding the "Member of" list entirely is done by hiding your "Friend of" list (http://www.livejournal.com/support/faqbrowse.bml?faqid=185).
However, FAQ 185 says:
you can choose to hide the entire list so that it does not display to other users when they are viewing your User Info page (http://www.livejournal.com/support/faqbrowse.bml?faqid=61).
FAQ 61, finally, says:
You have the ability to hide your Friend-of list by checking the "Hide "Friend of" list" option in your Personal Info page (http://www.livejournal.com/editinfo.bml). This will also hide your Member-of list. You can't, however, hide your Friends list or the list of communities you have posting access to.
Isn't that a bit of a wild-goose chase?
In my opinion, FAQ 200 should either link directly to FAQ 61, or FAQ 185 should also incorporate the information on hiding your "Friend of" list.
Or is there some reason for sending the user via FAQ 185, e.g. to mention banning of individual users?