Google has made it easier to rename users in the Administrator Control Panel by adding the ability to rename from the user information page.

Editions included:
Google Apps, Google Apps for Business, Government and Education

Languages included:
US English only (Next Generation Control Panel)

How to access what’s new:
Go to ‘Organizations and users’, select the user’s name to open the user information page, and click the ‘Rename user’ link next to their name.

For more information:
Please see Google’s help center.