How to Unlock an Excel Workbook
At times you may need to lock certain parts of your Excel workbook to keep others from moving, deleting, renaming, hiding or revealing worksheets in the file. You can also protect a shared workbook and specify how it is shared or track any changes that are made. Locking a workbook does not secure the file, and adding a password is optional. When you unlock an Excel workbook, others can open and modify it freely or restructure its worksheets.
Open the Excel workbook you want to unlock.
Select "Tools," "Protection" and "Unlock Workbook" from the toolbar. If you added a password initially (when you locked the file), you will be prompted to type it in. Click on "OK" in the "Unprotect Workbook" box. The workbook will be unlocked.
Select "Tools," "Protection" and "Unprotect Shared Workbook" from the toolbar to unlock a shared workbook. Enter the password into the "Unprotect Sharing" box if you inserted one initially. Then click on "OK." Click on "Yes" to remove the workbook's shared settings if you are prompted to.
Select "File" and "Save As" from the toolbar to remove the password from a password-protected workbook file. Click on "Tools" and "General Options" in the "Save As" dialog box. Remove the password from the "Password to open" field (to allow users to open it) and/or "Password to modify" field (to allow users to modify it) and click "OK." Click on "Save" to save the workbook without a password.