The Windows Taskbar will be display all the workbook windows of Excel 2010 if you have opened multiple workbooks. The Taskbar would display the workbook windows as shown below
Showing these workbook windows in Taskbar will be useful when you want navigate between these workbooks. But if you have more than 3 or 4 windows kept open then it would become unmanageable and your taskbar might look bit messy. Excel 2010 provides option for hiding these multiple workbook windows from getting displayed in Windows Taskbar.
Step 1: Click the File menu –> Select options.
Step 2: In the Options window, click Advanced tab.
Step 3: Scroll down to Display section and unmark the checkbox with label as Show all windows in the Taskbar.
Step 4: Click OK button to confirm and save the changes. After applying the changes, the Taskbar would display only one Excel window irrespective of the number of opened workbooks.