Hi,
You can try to uninstall Microsoft Launcher by opening your phone's Settings, click on Applications and then look for Microsoft Launcher. You can uninstall the app by clicking the Uninstall button. After uninstalling the application, you might need to restart your device. In the event that you'll experience any issues with changing your phone's launcher to default, we highly suggest that you contact the manufacturer of the device. They can provide you assistance with your concern because they have the expertise when it comes to navigating and managing the settings of your phone.
Reply to this thread if you'll need further assistance.