You can cancel you application before you pay the money. After you pay the money, we suggest you go ahead with your application for one full year. in case you want to cancel it after payment, you would be charged for the active month and the remaining amount would be refundable.

For example if you have created your application on the 18th of March and would like to remove your application on the 10th of April (or any time before 18th of April), you would be charged for one month and the remaining amount would be refundable. your payment would be for one year and the billing cycle is for one month.
If you have created the application on March 18 2012 and want to cancel or remove your application on May  12 2012, you would be charged for two months (March 18 - April 18 and April 18 - May 18).