Login to your profile, go to the transaction history and click on 'request for a refund'
Please note a refund will only be processed if it is requested within 48 hrs of the transaction. Once the fundraiser has been paid out, no refund request will be accepted.
Note: The refund will be the amount donated minus the payment gateway charges as per the actuals i.e. approx 0.5%-3% per transaction. In the case of foreign payments(Non-INR), there could be forex conversion charges also from your respective bank. It would depend on the bank, card, country etc. It would be best to check with your bank.