When trying to delete old logins that show no references in Usage window, you get the following error message:
Database Query Error
ORA-20076: Cannot delete db login for Master as references exist'
Although there is no reference shown in the Usage window, there are still references in place. They can not be seen under the current user but should be visible when logged in as sqloper.
You can try to log in with the SQLOPER user and delete the references shown in the Usage window, or delete it in sqlplus. Please contact Automic support for the statements.