You can choose to transfer to another registrar at any time during the time you hold your domain name licence. For more information see auDA's Transfers (Change of Registrar of Record) Policy.
You will need to contact the gaining registrar, i.e, your new desired registrar to initiate the registrar transfer. You will also need your Domain Name Password.
Please use the Recover Password tool at http://www.ausregistry.com.au/tools/recover-password in order to retrieve your domain name password so you can transfer it to another registrar. If the Registrant email address is incorrect you will need to contact the sponsoring registrar in order to update it.