Closing

Application.ActiveDocument.Close SaveChange:=wdSaveOptions.wdPromptToSaveChanges 
                                 OriginalFormat:=wdOriginalFormat.wdPromptUser 
                                 RouteDocument:=False 

All these arguments are optional
The RouteDocument is optional and can be set to True to route the document to the next recipient
If the document does not have a routing slip attached then this argument is ignored.

Application.Documents("document.doc").Close 
Documents("document.doc").Close 
Documents(1).Close 
objDocument.Close 

Close all Documents without saving

You can use the Documents collection to quickly close all the currently open documents.

Application.Documents.Close SaveChange:=wdSaveOptions.wdDoNotSaveChanges 

Exiting Word

Application.Quit SaveChanges:=wdSaveOptions.wdPromptToSaveChanges 
                 Format:=wdOriginalFormat.wdWordDocument 
                 RouteDocument:=False