I tried many tutorials but without changes. Here are my steps:
First, it is required to have root, Xposed Module and GravityBox installed. In GravityBox settings you can change Navigation bar width in landscape mode. I set it to 0% to completely hide it.
iGO Primo thinks that your device has physical buttons and goes fullscreen, but now you can not access buttons on navigation bar so I recommend you to turn Pie controls in GravityBox to access buttons by sliding from screen borders. There are more settings and you can customize them like you want.