According to this Link, CRUD functionality for the TreeView control is available starting with version 2.7.0. Do you have a working example you could share?
The TreeView component is not designed to mutate data and so there are no CRUD operations available in it.
The topic of the linked thread is about ObservableCollection and since 2.7.0 the component can work with it. Here i have posted a short working demo of that.