It’s under your account settings somewhere, I can’t remember exactly but it should say somewhere in the knowledge base.
In fact, I believe backups are made from a snapshot database that’s a few hours behind the live one, so there’s a chance if you go in right now and set up a backup schedule, then request an immediate backup, that this first immediate backup may still contain your missing journal. But you’ll have to be quick, it depends when the snapshot process runs vs when you mistakenly deleted the journal.
Edit: