You can make a change to, or cancel, a recurring donation that you have setup with an organization at anytime by signing into your donor account. Follow these steps to do so.
First, go to the donation page of the organization that you have the recurring donation setup with. Click Sign In in the upper-right hand corner and log in using the credentials you created when submitting your first donation.
When inside your account, click Recurring Donations in the navigation menu on the left
If you want to update the amount or frequency of your donation, click the Actions dropdown menu and choose Edit
If you would like to cancel your recurring donation, click Stop under the same menu as above.
You can also update the payment type by navigating to Billing under the left-hand navigation menu. You will see the card that is being used for the recurring donation listed, and can make changes to it by clicking Update