Unfortunately there is no built in option to turn it off but you can download app made by Samsung from Galaxy Store which is called Good Lock app. In that app you'll see Lock Star, tap on it and turn it On, in there under Style section long press on one of the style you like and tap edit. In there you'll see option called Item Visibility tap on it unselect the Help Text and that should turn off that display. Also From the app Good Lock you can also add some customization and features that are missing in Android Pie.
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