Hi @CorvusC,

Welcome to the Intuit Community and thanks for reaching out for support! Having the ability to make a customer inactive is a great way to stay organized and tidy your books. QuickBooks Online is a great tool that's able to show you the balance owed to you by your customers for invoices that you've sent them. I'd be happy to help!

To make a customer inactive follow these steps:

1. From the left navigation bar > select Sales and then Customers

2. Checkbox the customer you'd like to make Inactive

3. Click the drop-down arrow in the Action column and hit Make Inactive

For multiple customers;

1. Checkbox all customers you want to make inactive

2. From the  Batch Actions tab, hit the drop-down arrow choose Make Inactive

You're all set!

If you have any other questions or concerns, please feel free to reach back out.  We'd love to assist!