I bought a notepad programmed with W8.1, hence it came with no Windows 8.1 CDs, and I took advantage of the free download to upgrade to Windows 10. I now want to get rid of the notepad and need to wipe it clean and re-install the OS. But I've nothing for the OS. What do I do? I intend to use a highly recommended software to totally remove any possible trace to anything I'd put on the HD. That, to me, means blanked, cleaned, nothing remaining. Help!