src/Camunda/Service/TaskService.php
public function unclaim($id)
    {
        $options = [
            'headers' => [
                'Accept' => 'application/json',
                'Content-Type' => 'application/json'
            ]
        ];
        $resource = str_replace('{id}', $id, static::RESOURCE_UNCLAIM);
        $this->execute('POST', $resource, $options);
    }
public function unclaim($id)
    {
        $options = [
            'headers' => [
                'Accept' => 'application/json',
                'Content-Type' => 'application/json'
            ]
        ];
        $resource = str_replace('{id}', $id, static::RESOURCE_UNCLAIM);
        $this->execute('POST', $resource, $options);
    }
Unclaim task

@param string $id