When you install an antivirus suite other than windows defender on your system, windows turn off the defender. According to Microsoft, they turn it off because another software suite is already protecting the system. But if you want to run both programs on your device, you can enable it.

To Enable Windows Defender Antivirus on your Windows 10 device, follow these steps.

1. First, open settings app by clicking on the setting gear icon from the Start menu.
2. Once, you are in the settings app, click on the Update and Security option.
3. Once there, look in the left pane and click on the Windows security option.
4. Then, look for Virus and Threat Protection option and open it.
5. Click on the Virus and Threat Protection settings and proceed to the next step.
6. Now, turn on the toggle of Real-Time Protection to turn it on.

These steps will turn on the Windows defender on your device without any hiccups.