public void removeAdminAccount(String username) {
        if (adminList == null) {
            loadAdminList();
        }
        JID userJID = XMPPServer.getInstance().createJID(username, null);
        if (!adminList.contains(userJID)) {
            return;
        }
        // Remove user from admin list cache.
        adminList.remove(userJID);
        // Store updated list of admins with provider.
        provider.setAdmins(adminList);
    }
Removes an account from the list of Admin accounts, based off username, which will be converted
to a JID.

@param username Username of user to remove from admin list.
xmppserver/src/main/java/org/jivesoftware/openfire/admin/AdminManager.java