//Remove from a single line string
$output = "Likening ‘not-critical’ with";
$output = preg_replace('/[^(\x20-\x7F)]*/','', $output);
echo $output;

//Remove from a multi-line string
$output = "Likening ‘not-critical’ with \n Likening ‘not-critical’ with \r Likening ‘not-critical’ with. ' ! -.";
$output = preg_replace('/[^(\x20-\x7F)\x0A\x0D]*/','', $output);
echo $output;

http://daipratt.co.uk/

This will remove all non-ascii characters / special characters from a string.

PHP regex - Remove special characters from a string

php

PHP