Hide The Workbook
You can
use the View commands to hide the workbook, the entire Excel
file.
Try it:
Hide the Workbook
Go to
View-> Window ->Hide.

What Do
You See? The screen image on this page shows Microsoft Excel
with a hidden worksheet. Usually, the hidden workbook is reference
data that is opened when someone is working on a the data analysis.
The hidden workbook is open, but it is invisible.
Try
This Too: Unhide the Workbook.
Go to
View->Window_>Unhide.
You will
be prompted to select the hidden workbook.