For the rest of the QuickBooks Online versions, the automated invoice reminders covers all customers. We're unable to exclude a specific customer unlike in the Advanced version.
However, I do have options for you if you're using other QBO versions. You can temporarily turn it off if you don't have any other overdue invoices. Otherwise, reach out to your customer and tell them to disregard those overdue reminders in the meantime.
To turn off the invoice reminder temporarily:
Click the Gear icon, then choose Account and settings.