How do I delete a record from an array that has nested elements in it?

[AngryDev]

With the sub i have below...

Public Sub DeleteArrayItem(arr As Variant, index As Long)
Dim i As Long
    For i = index To UBound(arr) - 1
        arr(i) = arr(i + 1)
    Next
    arr(UBound(arr)) = Empty
End Sub

I can successfully remove a record from a simple array. But when the array gets complicated, I get the following error.

Only user-defined types defined in public object modules can be coerced to or from a variant or passed to late-bound functions

Here is a pic of the array from a watch windows. Lets say I want to delete a3Tree(1) for example.