You can record a payment for invoices to change the status from "Outstanding" in red to "Paid" in blue - this status sits under the invoice number as below:
To record a payment, click the blue "Pay" button as above and choose the "Payment type", fill in the "Amount" and click "Save":
If you do not have a card on file for this patient and you integrate with Stripe, then click "Add a card" as shown above and that will automatically take you to the patient file where you will be able to enter card details:
Your invoice should now say "Paid" in blue under the invoice number:
Once a payment has been made this can not be deleted or edited.