We have simplified this process for you!
So go to Finances > Transactions and select Actions to the right of of the STRIPE transaction you need to refund.
Click on Refund, to activate the Refund popup. Fill out the details and click on the Refund button.
Once you have clicked on the Refund button you will see the details of the refund in Transactions.
Note: You are not able to do partial refunds through Stripe.