For Walmart, customer-requested returns will automatically flow into Zentail and generate an RMA. In this case, you wait for the item to arrive at your warehouse. Once it arrives, you want to complete the return by processing a refund. Here's how:
Click on the order that was returned to your warehouse in the Return Requested section.
Click COMPLETE RETURNS
Select Full Refund or Partial Refund (select the amount you will be refunding) then click COMPLETE RETURN
Resolve an alert on the order by scrolling down to the bottom of the left sidebar and click RESOLVE (here you have the option to enter notes) then click SUBMIT RESOLUTION.
Refunds processing is not currently available for Amazon and eBay orders although this functionality is expected in the near future.