In Drupal, we can replace documents. 

  • If you go to content/Files,
  • search for MIME Type: pdf or docx
  • You will see a "Used In" column,  
  • Click on the link
  • Click on the Entity link
  • remove the old file 
  • Add the new file

This approach will not work on submitted form content, but form responses get deleted within the form interface.