Hi there, @Musick.

Allow me to share some details what will happen after you've moved your data from QuickBooks Desktop to QuickBooks Online.

When converting, there are some data that will not match because of the differences between the features and functions. In your case, there are two ways to close the billable expenses, here are the two ways to do this:

1. Adding bills to any invoices with zero amount to easily close the billable expense.
   
   
2. Open each bill and remove it by ticking the box below the Billable column.
   
   

Also, you can make the customer inactive by going to the Customers page. Here's how it looks like:

I've added this article that contains guidelines when converting your data file: Move your QuickBooks Desktop file to QuickBooks Online. This includes sub-articles about QuickBooks Online to convert your files successfully.

I'll be here if you have other questions regarding QuickBooks. You can always tag my name in the comment section. Take care.