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From my knowledge and use the PSDr does not install on the computer, it will extract temporary files each time the icon is opened.If you would like to delete the temporary files, you can press the Windows and R buttons on the keyboard (from the desktop) and it will open the Run box.
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I see you are unable to scan / install with the HP Officejet Pro 8600 onto your Windows 8.1 computer, I would like to offer a hand.I would like you to run the HP Printer Install Wizard on the computer to acquire the software, it will download and start the install for you.As for removing the PSDr from your computer, you should be able to just drag the icon to your trash can (on the desktop).
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