public void removeUser(String username, String groupName) throws NamingException {

        try {
            ModificationItem[] mods = new ModificationItem[1];
            Attribute mod = new BasicAttribute("member", getUserDN(username));
            mods[0] = new ModificationItem(DirContext.REMOVE_ATTRIBUTE, mod);
            context.modifyAttributes(getGroupDN(groupName), mods);
        } catch (NoSuchAttributeException e) {
            // If user is not assigned, ignore the error
        }
    }