Alliance admin's now have the ability to change their in-game alliance name. This feature is predominately in place to allow alliance owners from using trademarked names. It may be modified in the near future to allow full alliance voting on the name change to make it a long term feature.
To change an alliance name, the alliance admin/owner needs to click on the Alliance name which is underlined on the view alliance page. Inserting the name and then hitting save will make the changes.