How to turn off Windows Defender permanently
In Windows 10 Professional, you can disable Windows Defender via the Local Group Policy Editor (gpedit.msc) by enabling the Turn off Windows Defender policy in the following location:
Computer Configuration/Administrative Templates/Windows Components/Windows Defender
In Windows 10 Home, it can also be done via an elevated command prompt:
reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection" /v DisableRealtimeMonitoring /t REG_DWORD /d 1
To roll back:
reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection"
Type in Defender into the search bar, and click on the Defender program in the list. When Windows Defender opens, click Settings and turn off real time protection.
I just noticed that it will reenable it automatically after some time, geez.
I suppose you will could install some third-party antivirus software that does not flag hack tools and such as a threat.
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There is a third-party application called NoDefender to disable it permanently, but I have not tried it or can vouch for it or what it actually does to accomplish this.
I found this note on another website, but I am not sure if it is true or not. Better make a restore point anyway.
NOTE: The NoDefender utility doesn’t include an option to enable Windows Defender again. So we suggest you create a manual system restore point before disabling Defender if you want to easily enable Windows Defender again in the future.
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Another method is to rename the Defender program folder. This must be done from a Linux Live DVD or USB: C:\Program Files\Windows Defender.
Another method is to disable the Defender Service from starting in the Windows registry as it cannot be done from Services directly as options are grayed out.
Open regedit and go to
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinDefend
Open the subkey corresponding to the service you wish to change (WinDefend), and modify the value of 'Start' to equal either "2" (for automatic), "3" (for manual), or "4" (for disabled).
**Registry edits have the advantage for Windows Home or lower versions, as they do not have Group Policy Editor to do it as suggested by Nate's answer.
This isn't a solution to turn off Windows Defender entirely, but I think it's a better solution to what you're actually looking for. You can turn off Defender's Realtime Protection, without turning off Defender altogether. If you want to be able to use Defender to do on-demand scans (not realtime scanning), then this solution is useful.
Open up the registry editor with Start -> regedit.
Navigate to Computer > HKEY_LOCAL_MACHINE > SOFTWARE > Policies > Microsoft > Windows Defender
Navigate to Real-Time Protection. If that key doesn't exist, create it under the Windows Defender folder. (note the space between "Time" and "Protection")
Inside Real-Time Protection, add a new
DWORDvalue.Name it DisableRealtimeMonitoring and give it a value of 1.
You may need to reboot. This will now allow Windows Defender to run on-demand, but if you look in the Defender settings, real-time protection will be turned off and grayed out.