Hello there, cmoil. 

Thank you for reaching out to the Community. I am here to help you sort it out. We can simultaneously select multiple customers on the list to make a group of your customers inactive at the same time. Let me show you how to do it: 

1. Click Customers menu, then select Customer Center. 
2. Under Customers and Jobs tab, tap the drop-down, and choose All Customers. 
3. Hover your cursor next to a customer you want to make inactive, and then click when the cursor turns to an "X." 

That's it! Hiding your inactive customers from the Customers and Jobs list makes the file shorter and more manageable without deleting each customer’s historical data.   

To learn more about this process check out this relevant article: Customize customer, job, and sales reports in QuickBooks Desktop.

Please keep in touch if there's anything else I can do to help you succeed with QuickBooks. I've got your back. Have a great day!