The official way to remove PDF password is to use the Adobe Acrobat Pro tool. Method 1: Unlock or Remove PDF Permissions Password with Acrobat Pro In this tutorial we'll show you 3 simple ways to unlock or remove PDF permissions password (owner password) with ease. If there are duplicate/expired certificates, please delete them by highlighting the additional certificate/s and selecting Remove.Unable to edit a PDF document with read-only restriction? How do I remove printing restriction from a PDF file? When you forgot the permissions password (also known as owner password) of a secured PDF file, you'll be unable to edit, copy or print its contents. Note: There should only be one certificate here. Select Close in order to save your settings.Result: Your personal certificate should now be shown with the expiration date in the column headed 'Expiration Date' Scroll the page to reach HTTPS/SSL and then select Manage certificates.Result: Settings will open up in a new tab. Click on the Chrome menu and then proceed to click on Settings.You will be prompted to confirm the deletion. If there are duplicate/expired certificates, please delete them by highlighting and selecting Edit > Delete. The expiration date should be listed to the right. There should be a certificate under your name listed.Click My Certificates under Category in the lower left-hand corner of the sidebar.If necessary, click Show Keychains in the lower left-hand corner of the Keychain Access window. Under your Mac OS X account, go to Applications > Utilities > Keychain Access.Note: Safari and Chrome store your MIT CA (Certificate Authority) and personal certificate in a file known as a Keychain. See How do I test my MIT personal certificate?.Close the Certificates window, then click OK in the Internet Options window.The expiration date is given in the column headed 'Expiration Date'. Result: Your personal certificates should be listed. In the Certificates window, click the Personal tab.Click the Content tab, then click the Certificates button (middle of the window).See also How do I test my MIT personal certificate?.Click OK in the Preferences/Options window, and then close the Certificate Manager window.Result: The expiration date is given in the column headed 'Expires On'. In the Certificate Manager window, you should see your personal certificates listed (if not, click Your Certificates).In the Certificates subsection, click View Certificates.In the Preferences/Options window, click Privacy and Security, then scroll down to Security.On Athena, Linux, and Macintosh: open Preferences.

If you are looking for how to get certificates, see Certificates Landing Page

Firefox 40.0.3 pdf expired