Foxit PhantomPDF/Foxit Reader application (from version 8 to version 10) has provided ConnectPDF features for creating ConnectedPDF files, etc, so you may still have some PDF files that are ConnectedPDF PDF documents. A ConnectedPDF file can still be opened by any standard PDF reader. However, if you would like to remove the Foxit ConnectedPDF ID from the PDF file, Foxit is providing a tool to allow you to convert the ConnectedPDF into a normal PDF file.
You could easily convert ConnectedPDF PDF file into a standard PDF document by simply downloading the Convert cPDF to PDF tool from here and follow its on-screen instructions to complete the conversion.
In addition,cPDF-protected and enforced tracking cPDF document can't be converted. So if the PDF file was protected with Foxit ConnectedPDF protection, it is suggested that the PDF owner uses Foxit PhantomPDF or Foxit Reader version 9 or version 10 to open the ConnectedPDF protected file and select "Remove Security" to remove Foxit ConnectedPDF protection and protect it using other protection methods such as password protection, etc.
Note:ConnectedPDF related features have been removed in Foxit PDF Editor/Foxit PDF Reader since version 11.
Relative article:
Why doesn't the Connect menu appear in Foxit PDF Editor/Foxit PDF Reader