Windows Defender is Microsoft's anti-virus program that comes with the operating system (Windows 8, 8.1, and 10).
When another anti-virus program is installed, Windows Defender is disabled to prevent any conflicts between the two anti-virus programs. This happens when you install Cylance Smart Antivirus.
If you uninstall Cylance Smart Antivirus and you want to use Windows Defender, you must manually re-enable Windows Defender.
Enable Windows Defender
- Right-click the Start menu, then click Settings.
- Click Update & security.
- Under Update & security, select Windows Defender.
- Click Turn on Windows Defender Antivirus.