Hello there, @lscott1.
Good to see you here in QuickBooks Community. I'm here to help and provide some insights about deleting transactions in QuickBooks Online.
Once you deleted an invoice payment, the transaction will completely be deleted. However, if you want to check the history of the payment transaction, it will show in the Audit Log.
For additional reference, you can check this article: How to void or delete an invoice or other transactions.
Please know that I'm just a post away if you have any additional questions. Have a good day.