This is short tutorial on the steps required to change user details such as first name and last name in Google Apps Account. The changes done here would get reflected in Google Apps Account email addresses.
Login to your Google Apps Control Panel then click the Organization & Users tab.
In the Organization & Users screen, navigate to the User Information tab.
Click on the Rename User link to update your first name and last name details. This would display the following Rename user dialog box.
Enter the First name and Last name information in the respective fields and then click on the Rename user to apply and save the changes.