You can, if the campaign is still ongoing, but we recommend against it, because the project owners are counting on your help! If you want to cancel a donation, you must do so within the time period specified by the project creator.
Connect on Ulule, then go to "My transactions" tab of your profile. There, you will find a recap of all your contributions. Find the support you'd like to cancel and click on "Cancel the support"
If you supported a project using a bank card or Direct Debit payment (Sofort and Giropay): the amount you pledged will automatically be refunded on your bank card.
If you supported a project using PayPal, you will never be debited of this amount.