Subscription cancellations must be completed on the website. Sign into your account and head to your Profile drop down on the top right hand corner and select Subscription. From this page you will be able to view all of your current subscriptions including your coaching programs, macros, btwb subscription, etc.
Select "Cancel subscription" on the subscription you want to end.
Once you cancel your subscription, all your info, data and logged results will be saved to your profile. If you ever want to come back to BTWB, you'll be able to take a look at where you left off.