Application.ShowWindowsInTaskbar

Excel

This property is true if there is a separate windows taskbar button for each open file.
When set to true this property simulates the look of a single document interface (SDI) which can make navigating between open files easier.
If you work with multiple files (and have a lot of other applications open) you might want to set this false to prevent filling your taskbar with unnecessary buttons.
The default value for all applications is True.

Application.ShowWindowsInTaskbar = False 

Word

Application.ShowWindowsInTaskbar = False 

PowerPoint

Application.ShowWindowsInTaskbar = msoFalse