If you have lost access to your app or device without backup, you can still reinstall the correct code if you have the original master key, the code (or QR code) that you used to add your iCE3X account to begin with. You can re-enter that into the app and continue as normal.
If you do not have a back up of the master key you will need to contact the support team by opening a ticket here.
They will need to verify your identity before they can remove 2FA from your account and you should have access to it again. Check out this article on how to verify your identity.