- str_replace: documentation ( source)
<?php
$story = "<p>Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.</p><p>Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.</p>";
$result = str_replace(['<p>','</p>'],['',''],$story);
echo $result;
?>