PDF with javascript export pdf with flattened form fields and reset the pdf

I am using PDF XChange to create a reusable PDF document that once signed changes all the fields to readonly and then sends it as PDF to our company mail and then clears all the fields and changes them back to editable.

This already works fine but setting the fields as readonly isn't the safest way of doing things so I wondered if there is a way of exporting the document with removed/flattened form fields.

This is the current code for it:

var f = this.getField("X10");
f.readonly = true;

var subject = "X1"+" "+this.getField("X2").value+" "+this.getField("X3").value+" vom "+this.getField("X4").value;
var url = "mailto:mail1; mail2?subject="+subject+"&body=whatever";
this.submitForm({cURL: url, cSubmitAs: "PDF"});

var f = this.getField("X10");
f.readonly = false;
f.value = "";