Can I fix a beginning balance discrepancy by recreating a transaction if the deleted transaction was a bill payment?
Yes, you're right, Malakan!
If you've accidentally deleted that bill payment, just recreate it. And please don't forget to mark it as reconciled (R) so it will adjust your beginning balance.
The Reconcile Hub article has a lot of information about reconciling accounts in QuickBooks Online. I'm sharing it with you for your future reference.
As always, we are happy to assist you here. Have a nice day!