1-Open your Visual Basic Editor (Alt+F11).
2-Make sure the Project window is visible. If it isn't, go to View--
3-Make sure that the properties window is visible. If it isn't, goto
View-->Properties Window.
4-In the Project Exolorer, find your workbook.
5-One at a time, select the sheets within that workbook that you don't
want the users to be able to unhide.
6-While the sheet is selected in the Project window, go down to the
Properties window and change the Visible property to
xlSheetVeryHidden.
This will cause any sheet set to xlSheetVeryHidden to not be displayed
in the Unhide Sheets dialog box. If no sheets are hidden other than
those set to xlSheetVeryHidden, then the Unhide Sheets menu option
will be grayed out.