Renaming global user using command line tools are not documented in the documentation.
You cannot use etautil for this, but need to use ldapmodrdn.exe
This program (together with other ldap command line tools) is installed by default on the provisioning server.
LDAP object Rename operation is very specific operation that cannot be done through etautil nor ldapmodify tool because it changes DN object itself (meaning the object reference).
will give you a help screen
Here is a sample regardign Global User renaming operation (should be 1 line) :
ldapmodrdn %LDAPConnect% "eTGlobalUserName=test01,eTGlobalUserContainerName=Global Users,eTNamespaceName=CommonObjects,dc=domain,dc=eta" "eTGlobalUserName=test02"
You need to replace LDAPConnect with your own bind/host/port/password values. See the help screen
Be sure to use the copy of the ldap command located under the provisioning server's bin folder.