Way to turn off Default windows antivirus completely using Cmd? [duplicate]

Take ownership of the key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender. Now set the value DisableAntiSpyware to 1.

This stops Windows Defender.

p.s. Download link for the tool.

In newer Windows 10 Builds (1703, 1709), this is not working any longer. Windows prevents creating keys under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender.

Here, go to HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender, create a DWORD DisableAntiSpyware and set it to 1:

Now reboot and Defender should not start again.

Attention: DisableAntiSpyware is ignored for Windows 10 (1903 and newer versions) since August 2020:

DisableAntiSpyware is intended to be used by OEMs and IT Pros to disable Microsoft Defender Antivirus and deploy another antivirus product during deployment. This is a legacy setting that is no longer necessary as Microsoft Defender antivirus automatically turns itself off when it detects another antivirus program. This setting is not intended for consumer devices, and we’ve decided to remove this registry key. This change is included with Microsoft Defender Antimalware platform versions 4.18.2007.8 and higher KB 4052623. Enterprise E3 and E5 editions will be released at a future date. Note that this setting is protected by tamper protection. Tamper protection is available in all Home and Pro editions of Windows 10 version 1903 and higher and is enabled by default. The impact of the DisableAntiSpyware removal is limited to Windows 10 versions prior to 1903 using Microsoft Defender Antivirus.

I'm not sure exactly what you have researched already, but here are a few quick potential solutions for you.

TEMPORARY OFF:

1. Open Windows Defender by clicking the Start button Picture of the Start button. In the search box, type Defender, and then, in the list of results, click Windows Defender.
2. Click Tools, and then click Options.
3. Click Administrator, select or clear the Use this program check box, and then click Save. Administrator permission required If you're prompted for an administrator password or confirmation, type the password or provide confirmation.

LINK: http://windows.microsoft.com/en-au/windows/turn-windows-defender-on-off#turn-windows-defender-on-off=windows-7

PERMANENT OFF:

A big thanks to TOPGUNDCP for the possible solution here.

PS. I have not tested it (as I do not wish to disable my own Windows Defender), but this seems like a good starting point.

1. Open Admin Command Prompt and type: gpedit.msc
2. Manoeuver to: Computer Configuration->Administrative Templates->Windows Components->Windows Defender
3. Double click on "Turn Off Windows Defender" and select "Enabled" then click "Apply"

WARNING: After turn off "Windows Defender", you might not be able to turn it back on. I suggest before trying this, make a backup image so you can restore to the way it was.

LINK: http://www.tenforums.com/antivirus-firewalls-system-security/5879-permanently-disable-windows-defender-post234396.html?s=90095f90f13d22416a5d1751ede0bd64#post234396

One can disable the Real-time protection of Windows Defender via the Settings app, but this will be only temporary, as Windows will re-enable it automatically after the next reboot.

To permanently turn off Real-time protection, I list below two methods. Reboot is required after each one.

Method 1 : Using the Local Group Policy Editor

This method requires Windows 10 version Pro or higher.

• Open the Local Group Policy Editor (gpedit.msc)
• Navigate to:
  Computer Configuration/Administrative Templates/Windows Components/Windows Defender Antivirus/Real-time Protection
• Double-click Turn off real-time protection
• Select Enabled
• Click OK.

Method 2 : Registry editing

This method will work for all Windows versions.

Create and execute the following .reg file:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection]
"DisableRealtimeMonitoring"=dword:00000001

Changing these settings requires that Tamper protection be off.

For more information about this feature see the Microsoft article
Protect security settings with tamper protection.

For methods of disabling this feature see the article
How to Turn On or Off Tamper Protection for Windows Defender Antivirus in Windows 10.

However, turning Tamper protection off but not through the Settings app requires taking ownership of the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender\Features, which might cause problems in the future with Windows Update.