When you have completed working with one document and you wish to start another avoiding close the word window, you should clear the word window by using close command from File menu.
Click File Menu >> Click Close
If your document hasn’t been modified since the last time it was saved, then Word 2013 will close the document and clear your screen.
If your document was modified since the last time it was saved you will be presented with the option to re-save your document before closing.
If you choose to save for document for the first time when you close it, you will see the Save window we have just explored. Name your document, click Save and the document will be saved and close simultaneously.
You can also close your document by pressing keys Ctrl + W from keyboard.