You may be region locked. When you set your location, you're only able to choose between the languages your country supports. So, for example, you'd only find German in Germany.
You'll need to go to your Xbox's settings via the home screen and then change your location to one that would support English (United States or Canada, for example). Then, you should be able to select English as an option.
You can delete games by selecting it and holding left option button (VIEW) (the one with two rectangles) and pressing A and "unistall". The manual is digital and you can access it directly on console by opening application with "?" as icon.