Remove Android App Title Bar

I understand that these properties in the manifest:

android:theme="@android:style/Theme.NoTitleBar"     
android:theme="@android:style/Theme.NoTitleBar.Fullscreen"

can remove the title bar. However, I constantly check the Graphical Layout when I am modifying my app. When I look at the Graphical Layout I still see the title bar. I want to remove the title bar in a way that I don't have to see it during the development of the game.

1. In the Design Tab, click on the AppTheme Button

2. Choose the option "AppCompat.Light.NoActionBar"

3. Click OK.