How do you find your EA origin account for Battlefield Hardline?

You login to Origin using the email address and passwordassociated with your account.

This might also be able to help: http://help.ea.com/ca/article/ive-lost-or-forgotten-my-password-how-can-i-recover-it/

For a little while longer you might also be able to see some information about your account here:

https://profile.ea.com