Thank you for writing.
events will fire when the grouping is changed. The following snippet shows how you can determine if a group is removed:
sender, Telerik.WinControls.UI.GridViewCollectionChangedEventArgs e)
(e.Action == Telerik.WinControls.Data.NotifyCollectionChangedAction.Remove)
Detailed information is available here: Events
Do not hesitate to contact us if you have other questions.
Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Feedback Portal
and vote to affect the priority of the items