Well I am working on a game and I would like to know how I can remove the icons from the window since I would like to leave only the closing one so that the window looks clean.
Hey!
There is only one way to hide these icons, and that is to enter fullscreen mode using this action:
You can also replace At the beginning of the scene with any conditions you want. 
P.S. If your preferred language is spanish, we have a spanish section here on the forum if that is easier 
Also, use the same action to disable fullscreen, but change the first yes to no in the action. (Or close the game!)