In Word select File, Page Setup:

  • Settings – Page Attributes
  • Format for – Any Printer
  • Click Paper Size – click Manage Custom Sizes

Custom Page Size:

  • Click + to add new size – name it PDF borderless
  • Click in the paper size boxes to make 210mm x 297mm for A4
  • Make sure Non-Printable Area says User Defined, and change margins in boxes zero
  • Click OK

Go to Print menu:

  • Click on PDF – Save as PDF
  • Choose file name and save location
  • Click Save