All Menus that make up the default interface can be removed and/or replaced with your own via the Menu Manager. For a full rundown of the Menu system, see the "Menus overview" chapter of the Manual.
A series of text-based tutorials on menus can be found here.
The video tutorials also cover menu customisation in various ways. See the 3D tutorial's mention here, and the first-person tutorial's mention here.
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