How do I Unlock a PDF Document and Remove PDF Restrictions?

I’ve got a password protected PDF document from one my client. It’s not possible to contact him (he’s out on vacation) and ask for the right password. I can open this PDF document without any difficulty but it is not possible to edit or print it may be due to applied password. So I just want to ask if it’s possible to decrypt or unlock this PDF file and remove these PDF password restrictions.

I’m not doing anything wrong or inappropriate as I have all the rights to use this PDF file. Any help would be most welcome.

Update: Thank you guys for all the help but my problem is now solved. I unlocked my file by following the procedure mentioned in this article:

So don't post more answers. Thanks!

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