Elgg\Database\UsersTable::unban PHP Method

    public function unban($user_guid)
    {
        $user = get_entity($user_guid);
        if (!$user instanceof ElggUser || !$user->canEdit()) {
            return false;
        }
        if (!$this->events->trigger('unban', 'user', $user)) {
            return false;
        }
        create_metadata($user_guid, 'ban_reason', '', '', 0, ACCESS_PUBLIC);
        _elgg_invalidate_cache_for_entity($user_guid);
        _elgg_invalidate_memcache_for_entity($user_guid);
        return $this->markBanned($user_guid, false);
    }