Is there a way to change a short name in OS X
Use these steps to change the short username of an account on your computer:
- Open System Preferences
- Choose the "Users & Groups" preference pane
- If the padlock at the bottom left is locked, click on it to unlock it with an administrator password
- Control-click on the account in the users list
- A menu will appear with "Advanced Options…". Select that and you will get a sheet where you can change the account name.
There's a good knowledge base article, HT1428, on how to change the short name of an account.