For an individual spreadsheet, select Protect Sheet followed by Unprotect Sheet to remove password protections. For a workbook composed of multiple spreadsheets, select Protect Workbook followed ...

A complex Excel 2007 workbook could require multiple sheets. By default, Microsoft provides three sheets on each workbook, but you can add as many as you need.

You worked hard to put that Excel sheet together, now protect it from unintended damage.