Make sure you are logged into BigMarker. Then from your personal home page, choose the Channel that you'd like to upgrade, downgrade or close/delete. You need Admin privileges to update a channel's billing plan.
Click the Channel Settings tab. Then choose Subscription & Billing. In this section you can change your billing plan, or switch to the free plan. Keep in mind the free plan caps webinars at 5 people and doesn't offer recording. However, all webinars and subscribers stored and saved. This is recommended if you plan on hosting in the future.