In order to delete the recurring invoices, open "Accounting" > "Recurring" from your left-side menu.
If you are using the New Navigation layout, open the Expenses page from the Financials menu and switch to the Recurring tab.
Click on the invoice three-dots menu to open the drop-down and choose "Delete":
Or click on the invoice and open the "Actions" menu. Choose the "Delete" option from the drop-down menu:
You will see a pop-up window. Put the checkmark and click Confirm to save changes:
