When the Essential AddOn Suite installs, it applies a sample Theme as an example of a Theme you can build in the EAS Theme Changer AddOn. If you do not want this sample them for your NinjaTrader platform, it is very simple to change.
On the NinjaTrader Control Panel, go to Tools>Options
Click on the Skins dropdown and select one of the NinjaTrader basic skins
Changing the skin will require a NinjaTrader restart.