Try to put it like that
$content = strip_tags($text);
Or you can do it with regular expression like that:
$content = preg_replace('/<[^>]*>/', '', $text);
By this $content = strip_tags($text, '<p>');
you are allowing the <p>
tag in the string.
For more info see the link http://php.net/manual/en/function.strip-tags.php