Many pdf files has password protection which were created and encrypted by a former department manager.So, if you don't have the user password, you need to use some pdf cracker to crack the pdf, but you must be legal to do this.
I would like to share you a article about How to remove PDF password and restriction,which has made the whole process easy.
It saved me lots of time on this. I just shared the guide with you.
Hope it can do you a bit favor.
better you ask the real owner of the PDF, there is no other way as how to open the software, you need to ask the old manager to get you the passwords, check the contract of old manager, he will be bounded to return everything related to office, these passwords are also covered in that office agreement!
dekkerlaura88: please read the forum rules before replying to more posts. Hacking tools, such as those you are suggesting, violate the forum rules and will get you booted off!