Question: how to make a pdf unfillable?
Answer: Step 1: Open the document in Acrobat. In Adobe Acrobat, choose the Fill & Sign or Prepare Form tool and select a file to upload. ... 
Step 2: Select File > Print. Once you have completed the form, you're ready to flatten it. ... 
Step 3: Select the PDF printer. ... 
Step 4: Save to specified location.