How to Turn On or Off Microsoft Defender Antivirus in Windows 10  

Hello Peter,

Just to verify, do you have Tamper Protection turned off?

I don't know because I can't find it or Security at a glance

See if you may be able to open Windows Security using an option below instead.

Open Windows Security in Windows 10

The Windows Security entry doesn't exist
When I search for "Security" it finds Security at a glance but when I click that it gives me the You need an app for Windowsdefender popup.
The only "Defender" item I have is Firewall.
No other Security items exist.
I've tried looking in GPedit.msc, no go thus far.
I have MBAM installed so it is protected.

As a test, see if this below will open Windows Security for you.

1) Open Run (Win+R)

2) Copy and paste windowsdefender: into Run, and click on OK.

Popup "You'll need a new app to open this "windowsdefender".

From what I have read it looks like my old employer would have neeeded to subscribe to an Enterprise security product in order for me to have anything like it.
As I'm no longer on that grid, I'd best ditch W10E and concentrate on Pro.

Ah, on domain then.

Yep. thanks anyway ;-)