How to hide the button near the QAT?

Are you saying you want to hide the Customize QAT button that appears immediately to the right of the QAT? Right now there isn't an option for that. Can you reply with more info about why you want that hidden? Thanks!

What I want to hide is the little menu (that shows the options of:
Customize Quick Access Toolbar,
Show below the ribbon
Mimimize the ribbon).

I provide my users with other buttons doing the same behavior and I don't want them to have this menu.

If this menu cannot be hidden, is there a way to change the text (into another language)?

Thanks,

Yes, all the UI text in our WPF products can be customized via string resources. Please read the String Resources help topics for more information.

Thanks.

Is there an option to hide this menu, or set it disabled?

Well there are various options on the Ribbon control that govern what options are displayed, etc., but you can't hide the menu as a whole.