GroupDocs.Conversion provides the PdfLoadOptions class to give you better control over how the source PDF document will be processed. The following options could be set:
setFormat allows you to specify explicitly the type of the source document. Available options are: Pdf, Epub, Xps, Tex, Ps, Pcl.
setRemoveEmbeddedFiles whether to remove the embedded files from the source document during the conversion.
setPassword specifies a password to unlock the protected document.
setHidePdfAnnotations specifies that annotations in the source document should be hidden.
setFlattenAllFields specifies that all fields in the source document should be flattened during the conversion.
Flatten all fields
The following code snippet shows how to convert a PDF document and flatten all fields: