Is there a way to stop payroll posting journals to the nominal ledger?
Welcome to the Community. I'd be glad to help share information about the nominal ledger in QuickBooks Online.
QuickBooks Online currently uses the concept called Source and Targets for the transactions on the system. When you run the General Ledger report, the data populating will be both source and target data from a specific company.
For more insights on the concept, such as the reports, I'm adding the article on this: