Unless you define a user name or UID number that conflicts with an existing one, you should never need to modify a user account's login name or UID number. Use the following steps if two user accounts have duplicate user names or UID numbers:
If two user accounts have duplicate UID numbers, use Admintool to remove one account and re-add it with a different UID number. You cannot use Admintool to modify a UID number of an existing user account.
If two user account have duplicate user names, use Admintool to modify one of the accounts and change the user name.
One part of a user account that you can change is a user's group memberships. Admintool's Modify option lets you add or delete a user's secondary groups. Alternatively, you can use the Groups window to directly modify a group's member list.
You can also modify the following parts of a user account: