In the Offer tab, you will find the information about the customer's active offers. 

Images and status sign in the “status” column give clear indications how an offer was added and in what state the subscription is in 

By clicking on the "Add entitlement" button you can add an offer to a user account manually. The user will never be charged for this offer.

By clicking on the "Add discount" button you can add a promotion code to give a discount on the next invoice. The button is only visible when the user already has an active subscription.

Subscription offers have a cancel button. When you click on it the subscription will be cancelled but is still active until the end of the billing period.

When a subscription offer is in the cancel state a "reactivate" and a "delete" button will appear. Reactivate means that the cancellation will be reversed and when you click on delete the offer will be removed immediately.

The other regular offers have only a delete button which removes the offer immediately.

Default and 3rd party offers can't be removed from a user account through the console. 3rd party offers like In-App purchases need to be cancelled by the customer in their store account.

You can find detailed information on the offer by clicking on the "See more" button.

The offer history can be found in a separate submenu.