Windows Defender isn’t the best antivirus software (even Microsoft admits its first-party solutions aren’t ideal), but it’s enabled by default on Windows 10 Home. In fact, the only way to disable it is to install something else.
In a strange turn of events, Microsoft has made its Windows Defender feature a permanent fixture of Windows 10. You can temporarily disable it, as you see in the screenshot above, but you can’t turn it off permanently. If it stays off for too long, Windows will turn it back on.
The one caveat to this rule, as pointed out by tips site MakeUseOf, is to install third-party antivirus software.