You can get the email from Optus Live Chat (assuming it is an Optus email?) answering various security questions.
If having an email doesn't help opening the OptusX (which it likely won't) then you will need to factory reset the phone (scrub all data). There doesn't appear to be a way to do this without logging into the phone directly other than using iTunes:
You will need to use a computer (Windows or Mac) with the latest version of operating system and iTunes software installed.
Once you have everything ready, follow these steps:
Not iPPhone X but this one:
For Android there is not much you can do: