PDF documents can be protected by the creator by disabling some functions such prevent printing, copying or editing the documents. Thats the reason why most users choose PDF format to share and transfer documents. They need to keep their content from being copied or stolen.
There are several ways to remove this PDF protection. You can use online or offline ways.
1. Online Ways
I found two good sites that offering a service to unlock your PDF files, PDF Cracker and PDF Filler . Both sites will ask you to upload your PDF files and all you do is just wait them finish their jobs.
To unlock a PDF file, enter it's location in the "PDF file to unlock" field, by either typing it in the field or clicking on the "browse" button, then navigating to it's location.
The unlocked version of the PDF will be displayed in a new browser window, opened in the default PDF application for your system (usually Adobe Acrobat Reader)
Surely you will need a very good internet connection to do this, otherwise you'll get stuck when try to upload the PDF documents or view the result.
2. Offline Ways
For you who don't have a good internet connection, just like me, you can download and install Freeware PDF Unlocker.
Download and Install in your PC. And you will find PDF Unlocker icon in your desktop.
How to use it?
Just drag your PDF documents (that you want to unlock) to PDF Unlocker icon and then PDF Unlocker will create a new pdf document without the restrictions.
PDF Unlocker Process
You can also try other software, OmniPage Software (468 MB). It has some extra features, this tools enable you to print to PDF, turn text documents into audio books and add digital signatures to your electronic documents. But you must pay for this.
Conclusion: Freeware PDF Unlocker is the best solution to remove PDF Document restrictions, it simple and free.