To cancel one of your author subscriptions, head to your User Settings from the dropdown menu in the top right corner. Under Your Subscriptions, you’ll see a listing of every author you’re subscribed to and the level of each subscription. There will be a link to Unsubscribe on each entry.
Please be aware that, by default, all cancellations are effective at the end of the current billing cycle. You won’t be billed again, but neither will you be refunded for the remainder of the month.