Let's turn off some features to stop QuickBooks from sending reminders automatically, @dqrichards1569.
It's possible that the Automatic invoice reminder option was turned on that's why it sends automatic reminders. Let's turn off this option so you can get back to working order.
I'm adding this article to learn more about the feature: Automate invoice reminders in QuickBooks Online.
Please know that I'm just a reply away if you need any further assistance managing invoices. Wishing you and your business continued success.