Disabling Windows Defender Security Center in Enterprise (1703)

Hi,

A few answers :-)

Let's start with - we do NOT support any manual changes to the registry, so those changes are not documented and not supported. 

The GPO setting you set is supported, but all that does is disable Windows Defender antivirus, which would have already been disabled as you are using Symanten Endpoint Protection. Windows 10 only allows you to run 1 antivirus in real time protection at a time.

We know it's a bit complicated, and we are working in the Fall's Creators Update to make it better - but there are actually two things you see:

1. Windows Defender Security Center (WDSC) which has an overview of a lot of built-in Windows safety features (AV, Firewall, Device performance). So it's relevant even if you use SEP for AV. We currently do not support disabling this UI, but we have heard this feedback and are working on this (though no commitment/timeframe).

2. Windows Defender Antivirus. What you knew before simply as "Windows Defender". That, you can disable via GPO ( You can read more: https://docs.microsoft.com/en-us/windows/threat-protection/windows-defender-antivirus/prevent-end-user-interaction-windows-defender-antivirus )

Hope that helps,

Amitai