No, this is not possible. Every cancellation needs to be requested from us. Your booking was made through a car rental broker who is responsible for managing the charges, including cancellations. That means, the cancellation is only valid when requested from Car-rentals.com.
Please note that when you cancel your reservation within the last 48 hours before the start of your rental, this can result in a cancellation fee depending on the terms and conditions of your offer. If you are in need to cancel your reservation last minute or at the rental desk, we advise you to contact us via phone by calling the number in your confirmation email.