As stated here: http://confluence.atlassian.com/display/JIRA/Configuring+User+Directories#ConfiguringUserDirectories-UpdatingDirectories

You cannot edit, disable or remove the directory your user belongs to. This precaution is designed to prevent administrators from locking themselves out of the application by changing the directory configuration in a way that prevents them logging in or removes their administration permissions.

Please make it so that when a user is logged in and they see a directory they cannot edit because they belong to that directory a warning or visual indicator is present saying something to the effect of "You cannot edit this directory because you are logged in through it, please log in as a locally authenticating user to edit it"