The deleteJob function ain't work well

[iTryIt]

My env.
system: centos 7
jenkins ver.1.612
php5.6.*
curl(system) ver.7.29.0
using nginx

I don't know what's wrong with jenkins or curl. It seems that one of them can't recognize the POST method unless I send a empty array POSTFIELDS with it.

public function deleteJob($jobName){
  /*
    ******
  */
  curl_setopt($curl, \CURLOPT_POST, 1);
  curl_setopt($curl, \CURLOPT_POSTFIELDS, []); // the deff line
  /*
    ******
  */
}