Microsoft also stated about anti-virus being removed upon installation of Windows 10. This is from Microsoft's website:
Many applications, files, and settings will migrate as part of the upgrade. However, some applications or settings may not migrate.
◦For anti-malware applications, Windows will check to see if your anti-malware subscription is current (not expired) and compatible during the upgrade.
◦If the anti-malware application is compatible and current, your application will be preserved during the upgrade to Windows 10.
◦If the antimalware application is incompatible, Windows will uninstall your application while preserving your settings. After upgrade is complete, if your antimalware provider has informed Microsoft that it has made a compatible version available for your active subscription, Windows will notify you to install the latest version available with the settings that were set prior to upgrade.
◦If your anti-malware subscription is not current (expired), Windows will uninstall your application and enable Windows Defender.