You can cancel your Bigin account subscription from Bigin itself. Once it is cancelled, you will be moved to the free edition and you still will be able to access your data and use the features that are available in the Free edition.
To cancel your Bigin account subscription
Go to your profile and click Manage Subscription.
Click the Change Plan button.
Select Free in the Confirm Order page.
Click Proceed to downgrade and then click Move to Free edition.