Windows 10 uses the built-in Windows Defender as the default antivirus software if you have not installed third-party antivirus software like McAfee Free Antivirus and Avast Antivirus for Windows 10. The Windows Defender is automatically turned off when you install a third-party antivirus program. However, when Windows Defender is the default antivirus, Windows 10 10 doesn’t allow you to disable Windows Defender for obvious security reasons. In short, Windows 10 doesn’t allow you to easily remove or disable the Windows Defender program. There is a setting under the Windows Defender section of the Settings app to turn off Windows Defender real-time protection, but the catch is that Windows Defender is automatically enables itself after a short period if it finds that no other antivirus is installed on your Windows 10 PC. If you want to run Windows 10 by disabling or Windows Defender and without installing a third-party antivirus program, you can either use Group Policy or Windows Registry to disable Windows Defender program in Windows 10. Complete the given below instructions to disable Windows Defender in Windows 10. NOTE: We haven’t tried this method on Window 10 Home edition and hence can’t say if it works on Home edition as well. The method works great on Windows 10 Pro. Method 1 of 2 Disable Windows Defender using Group Policy This method applies to the Pro edition of Windows 10. If you’re on Home edition, please refer to the directions in Method 2. Step 1: Type Gpedit.msc in Start menu or taskbar search box and then press Enter key to open Local Group Policy Editor. If you see the User Account Control prompt, please click the Yes button to continue. Step 2: In the Group Policy Editor, navigate to: Computer Configuration > Administrative Templates > Windows components > Windows Defender. Step 3: On the right-side, look for the policy named Turn off Windows Defender. Step 4: Double-click on Turn off Windows Defender to open its properties. Step 5: Choose Enabled and then click Apply button. That’s it! Method 2 of 2 Disable Windows Defender using Registry Important: We recommend you create a system restore point before manually editing the Registry. Step 1: Open Registry Editor by typing Regedit.exe in Start menu or taskbar search box and then pressing Enter key. If and when you see the User Account Control prompt, click the Yes button to launch Registry Editor. Step 2: Navigate to the following key in the Registry Editor: HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftWindows Defender Step 3: On the right-side, right-click on the empty area, click New, click DWORD (32-bit) value, and then name it as DisableAntiSpyware. Step 4: Double-click on DisableAntiSpyware and change its value data to 1 to disable Windows Defender. Restore the value data to “0” to enable the Defender again. How to remove Scan with Windows Defender entry from Windows 10 context menu guide might also be of interest to you.