If you press ESC the key binding gets set to NONE.
I do wish there was a forge api that could do two things:
1 many mods register keybinds that are context sensitive. I.e. Only apply if you are mounted (on the correct thing) or are holding / wearing a mod item. These keybinds could often easily share the same key if they weren't warned as a conflict AND the keybinds api could keep trying additional mods till one indicated that the context was met.
2 with regard to keys that open GUIs it would be nice to register a chorded keybinds. I.e. Ctrl/alt/shift+key. So, for example, M could open my map and Alt-M could toggle the minimap, Ctrl-M would open map options GUI and Shift-[Alt-]-M could cycle modes for the map or minimap. Up to 8 different functions per key are possible.