$url = "http://188.***.***.***/plugins/restapi/v1/chatrooms/".$roomName."/members/".$userJID;
    $curl = curl_init($url);
    curl_setopt($curl, CURLOPT_HEADER, false);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl, CURLOPT_HTTPHEADER, array("Content-type: application/xml", "Authorization : ******")); //I am using plugin.userservice.secret key here
    curl_setopt($curl, CURLOPT_POST, true);
    curl_setopt($curl, CURLOPT_CUSTOMREQUEST, "DELETE");
    $json_response = curl_exec($curl);

        $status = curl_getinfo($curl, CURLINFO_HTTP_CODE);
        curl_close($curl);