Microsoft seems to have removed an option in the registry that disables Microsoft Defender. The company continues to provide the option to disable through Group Policy, but the option for ordinary Windows users has ceased to exist (Home and Pro versions).
The Windows Defender is the default antivirus application that comes with Windows 10. Earlier versions of Windows such as Windows 8.1, Windows 8, Windows 7 and Vista also had it, but in the past it was not as effective as it only scanned for spyware and adware .
In Windows 8 and Windows 10, Defender has started to rely on Microsoft Security Essentials and has since offered better protection against all types of malware. Microsoft renamed the application to Microsoft Defender.
DisableAntiSpyware was a special option in the Registry and could be used to disable Defender. It was available in all versions of Windows 10, even Home and Pro. So it seems the company is changing that.
This setting is interrupted and will be ignored on client devices, from the August 2020 update, or in version 4.18.2007.8 of Microsoft Defender Antivirus.
Advanced users and administrators can use Group Policy and other related options to turn off Defender.
Note that Microsoft's move indicates that it does not want you to disable Windows security software. By this time, if you install any other security software, the Microsoft Defender Antivirus is automatically disabled by third-party software.
This may change in the near future, as Microsoft may add more restrictions (unless the major companies developing security software protest).