You cannot delete an invoice with a Medicare claim history. However, you can:
unlink the fee from the appointment so that you can delete the appointment; and
void the invoice line so that there is no balance outstanding.
To unlink a fee from an appointment:
Navigate to the invoice.
Click the Edit (pencil) icon next to the fee you wish to unlink.
The Edit Invoice line pop-up appears. Click the X next to the appointment.
RESULT: The invoice line is no longer linked to the appointment. You can now delete the appointment from your calendar if you choose.