$re = '`(https?:\/\/.*\.(?:jpg))`m';
$str = 'background-color:#000000; background-image:url(https://www.sample.com/free-videos/player-images/20170204-01.jpg); background-size: cover; position: relative;';
$subst = "";
$result = preg_replace($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