Let's turn off some features to stop QuickBooks from sending reminders automatically, YPWW. 

It's possible that the automatic invoice reminder option may have been turned on, causing those automatic reminders to be sent out. To get you back in working order, let's turn off this option together.

Here's how: 

1. Click the Gear icon, then select Account and Settings.
2. Select Sales from the left menu and go to the Reminders section.
3. Toggle the Automatic invoice reminders option to turn it off.
4. Hit Save, then Done.

I'm adding this article to learn more about the feature: Automate invoice reminders in QuickBooks Online. 

Another workaround is to delete the recurring template that you set up. To do this, you can check out this article for more detailed information and steps on how to delete it: Recurring Transactions in QuickBooks Online.  

Feel free to add a comment below if you have other invoice-related concerns. I'll jump right back in to answer them for you. Have a good one.