However, you can permanently disable Windows 10 Defender through Windows Registry. If you use Windows 10 Home, then you won’t have the Group Policy feature on your PC. It actually refers to the Windows Security app, not the antivirus itself.
The icon can sometimes linger on your Taskbar, but that doesn’t mean the process wasn’t successful. If you own Windows 10 Pro or Enterprise, you can use Group Policy to permanently disable Microsoft Defender. How to Permanently Disable Windows Defender?