$re = '/<(p|span).*?>/';
$str = '<td style="blabla">
<p style="blabla">
tekst <span style=blabla">more text</span>
</p>
</td>';
$subst = "<\1>";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php