Removing an Account
Only Cloud Account Administrators or Identity Domain Administrators can add or remove a user account, and only in the accounts they are assigned to manage.
To remove a user account:
Note that you can’t delete a user that belongs to a group. If you must do so, you must first remove the user from the group using the Identity Console and then delete the user account.
See Adding or Removing a User Account from an Administrator Role in Administering Oracle Identity Cloud Service.