There are 2 methods which you can choose to permanently disable Windows Defender in Windows 10
Method 1: Set “Turn off Windows Defender” settings to ‘Enabled’ from local group policy
1. Launch the Local Group Policy Editor on Windows via:
Windows Key + R > type gpedit.msc and press OK
Go to C:\Windows\System32\gpedit.msc
2. In the left pane of the Local Group Policy Editor window, navigate to the location below:
Computer Configuration/Administrative Templates/Windows Components/Windows Defender Antivirus
3. Find and click on Turn Off Windows Defender Antivirus on the right pane.
4. Switch the selection from “Not Configured” or “Disabled” to “Enabled“. Then click “OK” to apply the changes.
Method 2: Modify the registry to set Windows Defender to permanently disabled.
1. To do this, you may download the following file: turn_off_windows_defender.zip
2. Next, extract the file, and double click on turn_off_windows_defender.reg