Excel 2007 includes various options for securing worksheets. One of these security options prevents users from editing a specified range of cells but requires no password to open the document, and another uses a form of encryption that makes the user enter a password to open the file. If your file contains the latter, and you no longer want to require a password to open the spreadsheet, you can remove the encryption so that the file opens normally.
Open Excel 2007, then open the worksheet whose password you want to remove. Type the password in the "Password" dialogue box that appears, then click "OK" to open the file.
Click the "Office" button in the upper left corner, then click "Prepare." Click "Encrypt Document," then type the document's password. Click "OK" to remove the password protection.
Click the "Office" button, then select "Save" to save the worksheet without its password.