In Windows the active window can be closed with a key combination. This combination or keyboard shortcut can also be used to close programs.
The keyboard shortcut or combination for this is:
ALT + F4
If documents are to be closed in such a way, it should be made sure before that this was stored!
In most cases you will be asked to save the document before closing it. But you should always be on the safe side.
For a complete list of all keyboard shortcuts for Windows, you can also have a look here!