I've got some steps to delete an invoice in QuickBooks Online (QBO), HGAT.
If you happen to create an invoice with incorrect data and want to delete it, kindly follow these steps:
Go to the Sales menu.
Click the All Sales tab.
Look for the invoice that you want to delete.
In the Action column, hit the dropdown option.
Choose Delete.
You'll be prompted with a warning message, select Delete.
To learn more about deleting transactions, you may view this guide since it has a lot of information and steps that you may use for future purposes: Void or delete transactions in QuickBooks Online.