Navigate to the admin side>>left menu>>payments>>all transactions
Press edit on the deposit transaction and choose status “refunded” or “reversed” or any other status that is different from “complete” and the transaction amount will reverse to the user side.
It is reverse the balance on the user side, but if the user paid you real money using any live payment method or even bank transfer, you will need also to refund his money from your payment method panel you are using to get payments from your users.