When your computer is running a single instance of Excel, all workbooks that you open are opened in a workbook window inside the Excel window. You can also create new workbook windows for any worksheet in a workbook by using the New Window command (View tab, Window group).
For more information, see View two or more worksheets at the same time.
You can close each of these workbook windows one at a time, or you can close the whole workbook (including all of its workbook windows). To close all workbooks that are open, you can close the Excel window or exit Excel.
What do you want to do?
Close the active workbook window
Click the workbook window that you want to close.
In the upper-right corner of the workbook window, click Close Window .
Note: If the window is the only open window of the workbook, the whole workbook is closed. If there are more workbook windows of the same workbook, only the active workbook window is closed.
Close a workbook
Activate the workbook that you want to close.
Click the Microsoft Office Button , and then click Close.
Close all workbooks and exit Excel
Do one of the following:
In the upper-right corner of the Excel window, click Close .
Click the Microsoft Office Button , and then click Exit Excel.