I use the following codes to add security (with password) to a PDF which prevent it from being updated or content extraction.
StdSecurityHandler new_handler = new StdSecurityHandler();
// 2010-05-26, Raymond Lee, Set back master password on PDF
if ( owner_password != null )
// Set Permissions
But now I want to remove those permission from the PDFs which has gone through the above settings
And remove the password (i.e. permission security) such that other can modify the content before showing it.
I have searched through the google and PDFTron but cannot find example on this purpose.