Removing the password from a PDF file

I have a couple of ebooks as PDFs with passwords, however my ebook reader (sony prs600) doesn't seem to support PDFs with passwords. What is the easiest of removing the password from a PDF (I know the password, which presumably helps a lot). It's a bit annoying buying a book and then only being able to read it in front of a computer.

Solution 1:

With A-PDF Restrictions Remover, you can remove the password and other restrictions in a few seconds.

A-PDF Restrictions Remover is shareware ($10), try before you buy.

Solution 2:

https://mupdf.com/downloads/index.html

I tried the Win32 pdfclean binary for MuPDF 0.5: https://web.archive.org/web/20191119070425/https://mupdf.com/downloads/archive/mupdf-0.5-win32.zip

I was able to remove the password without having to know the source password.

pdfclean clean protected.pdf pdfwithnopassword.pdf

MuPDF, available for at least Windows and macOS (via Homebrew) has a free command line tool called mutool. I personally used it to remove the password on my American Express statement and merge all my separate PDF statements into one giant PDF. The command line is: mutool clean protected.pdf pdfnopassword.pdf