How to Protect a Workbook's Structure in Excel
You can secure a workbook’s structure against changes, such as sheets being added or deleted. You can also protect a workbook’s windows so that they are the same size and in the same position every time the workbook is opened.
The workbook is now protected. When you right-click the sheet tab, all the options for changing the structure are unavailable.
If you need to turn off workbook protection, you can do so at any time.
The protection is removed, and the workbook is editable again.