How to protect an Excel file
Users may want to protect an Excel spreadsheet file to prevent other users from adding, changing, or removing data. Protection can be configured for individual cells, a single worksheet, or an entire workbook. Data in the protected cells, worksheet, or workbook cannot be added, changed, or removed. It's also possible to protect macros within the workbook from being removed or changed. Protecting an entire workbook essentially turns the file into a read-only file.
To protect an Excel file, decide whether you'll be protecting a worksheet or a workbook, then find your version of Excel below and proceed. If you want to protect one or more cells, choose the option to protect a worksheet.
Warning: Protecting a single worksheet only covers that specific worksheet. Any other spreadsheets in the Excel file (workbook) will be left open and unprotected.
Excel 2003 and earlier
For Excel 2003 and earlier versions, to protect a worksheet or workbook, go to Tools > Protection and select either Protect Sheet or Protect Workbook.
In the window that opens, you can select several additional options, depending on whether you are protecting a worksheet or workbook. You can also enter a password to protect the worksheet or workbook further. If you enter a password, you are prompted to enter the password again for confirmation.
Excel 2007 and later
In Excel 2007 and later, the process is essentially the same, just with different tab names. To protect a worksheet or workbook, go to the Review tab and select either Protect Sheet or Protect Workbook.
Tip: To remove the protection from a workbook or worksheet, follow the same steps above. The options will now say "Unprotect" instead of "Protect."