In order to protect your information entered in the Excel file, you need to select the rows and columns that contain your data and to click on Protect Sheet from the Review tab. In the pop-up window, you can select the elements that you want users to be able to change and to enter a password for your information. Click OK and reenter the password. In order to remove the password, you need to select the sheet with your data and to press Unprotect Sheet. Enter the password and the spreadsheet will be unlocked. Click the Allow Users to Edit Ranges button and you will be able to give to a specific user permission to edit ranges in a protected worksheet. For further information, you can check the Microsoft Support web page.