I guess the scenario is you created an FA, created a journal line with that FA but didn’t posted it. And now, when you want to delete the FA (though no transaction is posted), system is giving you error.
If this is the scenario, then you need maybe a technical help. It happens that when you create a ledger account or FA and if you create journal line with dimensions, system creates Rec Id which has reference of FA and dimensions. Although transactions are not posted, system still assumes that there is transaction. If the Rec Id reference is deleted, then you can delete the particular FA record.
Maybe someone from technical background help you in pointing the table name, but i will suggest ask your developer to do that task.