I have approximately 350 "Invoice" type transactions that were inadvertently uploaded. Is there a way to delete them all at once (rather than tediously, one by one)?

Good day, jfkbunkie. I'm here to help you sort things out.
 

Yes, there is a way to delete the multiple invoices in QuickBooks Online. I'll walk you through on how to do it. Here's how:

1. Go to Sales and select the Invoices tab.
2. Tick the duplicate invoices and click the Batch actions drop-down arrow.
3. Select Delete invoices.

Along with the steps above, you can see the sample screenshot below for additional reference:

Then, you can use this article as a reference when manually recording the invoice payments. Also, you may want to visit here to know more about creating and managing the recurring invoice.

I would be glad to have you back in case you have additional questions with QuickBooks Online. Have a good one. Thanks! Take care!