To achieve this, I would suggest subclassing the RadTabControl and extending its logic. For example, you can create a DelegateCommand (or any other command) as a property of the customized tab control. Then you can edit the default control template and place a button and bind it to this custom close command. As the command is inside the tab control itself, you would have access to the container generator of the control, so that you can handle both Items and ItemsSource scenarios to get the containers and remove or hide them. This approach will also make the control reusable.
Please let us know if you need further assistance.
the Telerik team