I have Adobe Acrobat XI Pro. I want to remove the OPEN Password required from the pdf. How do I do that? By the way, there is no PadLock button showing in my toolbar.

I have Adobe Acrobat XI Pro. I want to remove the OPEN Password required from the pdf. I have the password.  How do I do that? By the way, there is no PadLock button showing in my toolbar.