OS: Mac, Windows
1. Create a new project or open an existing project in QuarkXPress.
2. Navigate to File menu >> Export As >> PDF
3. On the PDF Save window, click on Options >> It will open the PDF export options window.
4. Click on Color listed on left pane >> Select the Setup as Grayscale or Grayscale 100k (as per your requirement) and click OK.
5. Now, you may save the pdf >> It will be exported in Grayscale mode.