How to remove HTTP headers from CURL response?

Make sure you put set the header flag:

        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_HEADER, true );
        curl_setopt($ch, CURLOPT_TIMEOUT, Constants::HTTP_TIMEOUT);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, Constants::HTTP_TIMEOUT);
        $response = curl_exec($ch); 

Do this after your curl call:

$header_size = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
$headerstring = substr($response, 0, $header_size);
$body = substr($response, $header_size);

EDIT: If you'd like to have header in assoc array, add something like this:

    $headerArr = explode(PHP_EOL, $headerstring);
    foreach ($headerArr as $headerRow) {
        preg_match('/([a-zA-Z\-]+):\s(.+)$/',$headerRow, $matches);
        if (!isset($matches[0])) {
            continue;
        }
        $header[$matches[1]] = $matches[2];
    }

Result print_r($header):

(
    [content-type] => application/json
    [content-length] => 2848
    [date] => Tue, 06 Oct 2020 10:29:33 GMT
    [last-modified] => Tue, 06 Oct 2020 10:17:17 GMT
)

Don't forget to close connection curl_close($ch);

Just set CURLOPT_HEADER to false.