You can only cancel your purchase of STORM Credits if the status is "Pending." This means that you did not push through with your Bank Deposit or PayPal transaction. You may go to Wallet > Manage Credits and click on the "Cancel" button. Alternatively, you can just wait for the next 48 hours to pass, as our system will automatically cancel it.
For payments that have already been completed (status is "Verified" or "Approved"), you can no longer cancel the transaction. However, if you really will not be spending your credits, you may request for a Refund of your STORM Credits.