To rename an Essbase Server user, in the “Rename to” box of the Rename User dialog box, you enter a new username.
Rules for renaming users:
You cannot rename yourself or any user who is currently connected to Essbase Server.
Names must begin with letters or numbers and must adhere to the length limitations detailed in the Oracle Essbase Database Administrator's Guide.
Names can include any special character other than a backslash (\).
Names are not case-sensitive.
alter user (MaxL) in the Oracle Essbase Technical Reference
renameuser (ESSCMD) in the Oracle Essbase Technical Reference