pdf have two types password.
one is open password. you can use this tool
http://www.recoverlostpassword.com/products/pdfpasswordrecovery.html
PDF Password Recovery 5.0 is an easy-to-use tool designed for removing asswords added to Adobe Acrobat PDF documents. It helps to decrypt protected Adobe Acrobat PDF files, which have “owner” password set, preventing the file from editing(changing), printing, selecting text and graphics(and copying them into the Clipboard), or adding/changing annotations and form fields. Pdf decrypt is being done instantly. Decrypted file can be opened in any PDF viewer without any restrictions—i.e. with edit/copy/print functions enabled. All versions of Adobe Acrobat are supported. It also recovers document open passwords.
another is edit/print password. you can use this tool
http://www.advancedpdfconverter.com/products/pdfpasswordremover.html
Advanced PDF Password Remover is a small and easy-to-use tool to decrypt protected Adobe Acrobat PDF files, which have “owner” password set, preventing the file from editing, changing, printing, selecting text and graphics and copying them into the Clipboard, or adding/changing annotations and form fields. Also It can remove the user/open password which protects the PDF files from opening if you know the password. Decryption is being done instantly. Decrypted files can be opened in any PDF viewer without any restrictions. All versions of Adobe Acrobat (including 9.x, which features 128-bit encryption) are supported.