It would be nice to have this as an option, nhac.

For now, you can only remove the REF NO. in a transaction since customizing the register is unavailable. I'll make sure to let our product engineers know about your suggestion. 

We always update the features in QuickBooks Online, and this preference might be added in the future. You can visit our blog here: https://quickbooks.intuit.com/blog/ to see what's new in our platform.

I'm just a few clicks away if you have any other questions or suggestions. Thanks.