You may have observed that you are no longer able to rename users as of NetWeaver Release 7.3…
Please be advised that this feature has been removed in standard.
For further details you might consider have a look at SAP Note 1694357.
In the past, renaming was technically simply a copy of the user with subsequent deletion of the old one. Therefore, if you really need that functionality, please use the copy function instead.
You can get additional information in Identity Management.
Hopefully it will be helpful… feel free to share your thoughts on that matter…