src/AbstractTransport.php
public function withoutHeader($header)
    {
        $object = clone $this;
        $headerName = $object->normalizeHeaderName($header);
        if (isset($this->configs['headers'][$headerName])) {
            unset($this->configs['headers'][$headerName]);
        }

        $object->request = $object->request->withoutHeader($headerName);
        return $object->buildConfigClient();
    }
public function withoutHeader($header)
    {
        $object = clone $this;
        $headerName = $object->normalizeHeaderName($header);
        if (isset($this->configs['headers'][$headerName])) {
            unset($this->configs['headers'][$headerName]);
        }

        $object->request = $object->request->withoutHeader($headerName);
        return $object->buildConfigClient();
    }
With Added Current Headers

@param mixed $header
@return static