Here is a tutorial to lock or hide only the formula cells in an Excel workbook. You can also lock formulas in all worksheets in a workbook.

Learn how to use Excel’s Allow Edit Ranges feature to assign editable cells, protect data, and streamline collaboration in shared workbooks.

If you have sensitive data you'd like to keep from prying eyes in a Microsoft Excel file, the easiest way to protect it is with Excel's built-in password tools.