PDF files can be protected with a password, this is easy to do with any file creation program and allows you to send confidential documents so that they can only be read if authorized. In reality, however, the protection of PDF files can often be very weak and can be removed more or less easily, in many cases. It is certainly very easy to remove the protection from a PDF if you know the access password, and then make it freely accessible.
With some programs, then, you can also try to remove protection even if you do not know the password, even if it may not always work (it all depends on the type of encryption used for protection).
To remove protection from a PDF whose password you know, you can use Google Chrome as a PDF reader very easily. Then open the PDF by dragging it to a Chrome tab, enter the read password and then print the PDF to another PDF. From Chrome, then right-click on the open PDF and go to Print .
Press the Edit key under Destination and choose Print to PDF. The new file will be unprotected. This is particularly useful if you receive medical reports or protected bank documents, to avoid having to remember the password, which can be different each time to read them. It is therefore advisable to do this job every time, at the first reading of a protected PDF, to forget the password forever.
Alternatively, if you don't want to use Chrome, you can download a small portable program that removes passwords from PDFs.
BeCyPDFMetaEdit, portable and free that does not require installation, allows you to open a PDF and change the security properties so that the password is no longer required.
If, on the other hand, there is a PDF of which the access password is unknown, the tools to be used to unlock a protected PDF are others, some of which I have already spoken, simple and which should almost always work (unless a strong protection algorithm is used).
1) PDFUlnlock is the site that allows you to upload a PDF for free and to re-download it completely without protection. It is so simple to use that it looks incredible, albeit with some limitations. In particular, it is possible to upload on the website only PDFs of maximum 5 MB in size.
2) SmallPDF, a popular site that provides the ability to compress PDFs, also has a tool for removing password protection for free.
2) PDF Unlocker is a free program, with the latest update in 2015, which allows you to unprotect PDFs.
3) Free PDF Unlocker, a small free program to disable the protection of a PDF even if you don't know the password.
4) PDF Security Remover Software is a non-free program, which you can still try for a limited period without paying anything. According to what is written on the site, this tool removes the password from any PDF, removes all types of restrictions on copying, editing, printing, and allows you to perform copy and paste actions of the text.
Similar paid programs that you can try for free are also Enolsoft for MAc and Jiohosoft PDF Password remover for Windows and Mac
5) PDFCrack is the real program to use in case you are dealing with a PDF protected with encryption, to recover the password and disable it. To use this tool, you need to extract it to an easy to reach folder, such as C: \ download \ pdfcrack. In the same folder, to make things easy, move the PDF whose protection you want to disable. Then open the prompt as administrator by looking for it from the Start menu (in Windows 10, right-click on the Start button). Change the folder with the cd C: \ download \ pdfcrack command . Now run the pdfcrack document.pdf command and wait hoping that it will work, until the password to be used to access appears.
6) QPDF is another command line tool that tries to remove the encryption of a PDF in order to unlock it even without a password. This tool works like PDFCrack, from the command line on the DOS prompt.
The command to be launched with QPDF is qpdf --decrypt document.pdf document-unlocked.pdf (remember to put the document.-pdf in the same folder where the qpdf program is extracted.
