If you have forgotten the password to an old pdf you just want to print, you can use imagemagick. From the commandline (Terminal) type:
convert -density 300 nonprintable.pdf printable.pdf
It will convert the pdf to a series of images. This means that you will not be able to select and/or copy the text of the pdf. The density option sets the resolution of the images in the resulting pdf to 300dpi.
reply to comment
If you have forgotten the password to an old pdf you just want to print, you can use imagemagick. From the commandline (Terminal) type:
convert -density 300 nonprintable.pdf printable.pdf
It will convert the pdf to a series of images. This means that you will not be able to select and/or copy the text of the pdf. The density option sets the resolution of the images in the resulting pdf to 300dpi.