Microsoft’s digital assistant Cortana is now available as a standalone app on Windows 10 May 2020 Update. By default, Cortana ‘app’ is added to the Startup programs which are automatically run when you turn on your PC. If you don’t use Cortana or you want to disable its background presence, you can switch off the feature by clicking the ‘Disable’ button at the bottom-right of the Start menu. You can always reinstall the Cortana app by downloading the package from the Microsoft Store.
Source: https://www.bleepingcomputer.com/news/microsoft/how-to-uninstall-cortana-in-windows-10-2004/