If you have a requirement that you want to close a word document but without closing the Word application then you can do the following.
Using File Menu.
Click on the File menu and select Close from the list of available menu option. This would close only the document.
Using Keyboard Shortcut.
The Keyboard shortcut for closing a word document is Ctrl + W
Using Quick Access Toolbar.
Another way of accessing the Close command is through Quick Access Toolbar. You can have the Close command by Customizing the Quick Access Toolbar.