It’s easy to protect excel worksheets by hiding it and equally easy to unhide it as well.
How to Hide
1. Select a worksheet
2. Goto Format > Sheet > Hide to hide an entire worksheet.
How to Unhide
1. Goto Format > Sheet > Unhide and select the worksheet you want to unhide.
As you can see, unless you protect the worksheet/workbook, anyone can select Format > Sheet > Unhide to see the hidden sheet.
A Better way to Hide (Without Password)
You want it, so here’s another option:
1. Press Alt-F11 to display the Visual Basic Editor
2. In the Project window, expand the folder Microsoft Excel Objects, and select the sheet to hide.
3. Press F4 to display the Properties window (if it’s not already shown)
4. Set the sheet’s Visible property using the drop down box to 2 – xlSheetVeryHidden.
5. Users won’t be able to unhide the worksheet such as using Format > Sheet > Unhide as it won’t be listed anymore on the list of hidden worksheets.
5. Again, there’s still workaround to unhide the sheet, if the user knows how. To unhide the sheet, repeat these step, but set the Visible property to 0 – xlSheetVisible. Let’s just assume that less people knows about this and thus it’s a bit safer than the previous option.
Best way to hide and protect
Just protect your worksheet/workbook under Tools > Protection… and set a password for it.