How do that?
The app doesn't remove the notch per se, it just makes the notch invisible by placing a black bar across the tops of images that you must then assign to your Wallpapers in the iOS settings. Nevertheless, the end result looks like a traditional unibrow status bar, instead of the two brows currently found at the top of the iPhone Xs home and lock screens.
# App changes your wallpaper to adjust for the notch.
P/S: This app was made for fun. Technology is awesome, lets share a smile.