Go to Dashboard>>Frontdesk>>Bookings.
Select the booking you want to make a Refund Full/Partial.
Go to the Cancellations tab.
Press the Refund button, it will bring a Popup, where the partial/full refund amount would be mentioned.
You can refund the amount set or can change the amount to a Partial/Full amount.
All the refunds have to be done via your Payment Gateway dashboard (Stripe/PayPal/RazorPay).
This is to capture the amount refunded.