To refund a Cash payment, you will need to refund a guest in person and then open the guest's billing screen to post it in the system.
Once you are in the billing screen of the guest, click on the +Payment button and select Cash payment.
Enter an amount in negative, click Create button:
Refund will appear in the billing screen of the guest in positive:
To close this refund, we will post a negative Accommodation item so the Revenue for an extra night will be deducted from the Accommodation:
Now when the bill is balanced, we can close it.