I have some method like:
public void RemoveItem(ObservableCollection collection, SomeClass instance) { if(collection.Contains(instance))
If the item you intend to remove has something like a code/id you could compare to other item, you could do something in the lines of:
foreach (var item in itemSet) { if (item.ItemID == itemToCompareTo.ItemID) { itemSet.Remove(item); break; } }