A: You can use "Advanced PDF Tools Command Line" and Notepad.exe applications to edit XMP in PDF file, you can use "Advanced PDF Tools Command Line" to extract XMP from PDF file first, use Notepad.exe to edit it, save to a new XMP file, then you can use "Advanced PDF Tools Command Line" to insert this new XMP file into original PDF file again.
Please refer to following command lines,
pdftools.exe -r -i C:\test.pdf > "C:\metadata.xmp"
You can open "C:\metadata.xml" file in notepad.exe application, remove unnecessary information from this XML file, modify it to meet your requirement, after you finished the modification, you can run following command line to insert new XMP file into PDF file,
pdftools.exe -i C:\test.pdf -o C:\out.pdf -e "C:\metadata.xmp"
Please refer to following web pages for more information,