Pdf is one of the most common text formats online. From Ebooks to codes all the available. Reason it's easy to prevent privacy since once you password protect it no one can copy it. Adobe Acrobat even has settings to prevent underside copying of the file i.e save as text is disabled. But you can use these software's to crack open those files .You can remove all restrictions.
Just use any of these fully legal software to do it.None of these are free so if you want full version just do torrent(p2p) download. Let me warn you that cracking open these files is considered illegal so don't do them unless you have by mistakenly locked your own file.
If you just wanted the password of your pdf file try Password Recovery Software
