Acrobat PDF documents can be protected or locked with password to secure the confidential and private by restricting others from opening the PDF file altogether by PDF creator, or limiting ability by readers to modify, print, copy or extract text and graphics from the PDF contents. The later case, where printing is allowed, but copying is not allowed, has an easy workaround that can unlock and remove the password protection.
Removing the password is useful if you have legal rights or are genuine owner to the PDF documents, but forget the password. The hack only works to disable the password protection if the PDF file’ security settings has password protected from allowing readers from modify or copy and paste, but allow users to print the document.
To remove such password which restricts users from content copying or text and image extraction, try to print the PDF document to a PDF printer or save as a new copy to create another PDF document stripped of the password protection. You will get another PDF document and it will be password-free. However, the new PDF document will probably treat its contents as a set of pictures, rather than text.
If you don’t have any PDF printer or creator, download and install PrimoPDF which installs a PDF virtual printer.
PDF Unlocker can do the job more efficiently.