file upload has an extra name Upload parameter. how do i get rid of this extra parameter?

I read that when I am using file.upload in adobe air, the following format is being posted. using the following code

var request:URLRequest = new URLRequest("http://www.yourdomain.com/FileReferenceUpload/fileupload.cfm");

    request.method = URLRequestMethod.POST;

    request.data = params;

    fileRef.upload(request, "photo");

XXXXXXXXXXXXXXXXXXXXXXX

------------Ij5GI3GI3ei4GI3ei4KM7GI3KM7KM7

Content-Disposition: form-data; name="photo"; filename="sushi.jpg"

Content-Type: application/octet-stream

(actual file data,,,)

------------Ij5GI3GI3ei4GI3ei4KM7GI3KM7KM7

Content-Disposition: form-data; name="Upload"

I am trying to send to an API web server and they are very strict with the parameters and do not handle the name="Upload" parameter.

How do I change this ?

Please help thank you.