If you have sufficient rights, you can refund transactions from the Orders area within the Store feature.
It is possible, after completing the above, the refund will fail. This is likely due to insufficient funds being available in your Stripe account. You need to have funds in your Stripe account to be able to return to the purchaser.
If this is the case, you can wait to refund the transaction shortly after other transactions have completed, before the funds for those transactions get swept to your bank account. Or you can use the Stripe interface to transfer funds from your bank account into your Stripe account so they are available for refunds.
We also suggest temporarily disabling automatic sweeps of funds from your Stripe account so that a sufficient balance remains in the account for you to refund the transaction. This is particularly true if the transaction is large.