You'll need the original Software Discs to restore the Mac. If you don;t need Apple's Operating system for anything and only want windows then you don't need the discs.
You may be able to install Windows 7 or 8 officially through Bootcamp. 10 will require more steps but should be possible. But it is a very involved process, and you will need a paid license of Microsoft Windows to install. Windows is not free. Also install discs or a downloaded image for Windows. Macs don't come with Windows.
See here: http://www.davidlenton.co.uk/2016/02/05/installing-windows-10-on-a-late-2008-macbook-pro-running-el-capitan/
The Apple Id should not be required for anything outside the App Store, and on a 2008 Mac should not be blocking anything and you should be able to log off of of the Apple Id currently signed in.
Why can't you log in with your Apple ID, what is stopping you exactly?
With Windows 10 installed It might still be useful and be able to run most current apps, but not really very fast.
You can try the steps here to restore the Mac using the recovery partition: About macOS Recovery - Apple Support
