RefDes can be reset by selecting a component or components and then perform 'Delete Property' on Ref Designator row in properties window.
But this does not work when the selection includes other objects such as global symbols(GND, VCC) or pins
Below Automation code is to automate resetting RefDes of selected components even though the selection includes other objects so that you don't need to adjust selection filter.
Set colPins = Application.ActiveView.Query(VDM_COMPPIN+VDM_PIN, VD_SELECTED)
If colPins.Count > 0 Then
For Each obj In colPins
obj.Selected = False
Set colComponents = Application.ActiveView.Query(VDM_COMP, VD_SELECTED)
If Not colComponents.Count < 1 Then
For Each oComponent In colComponents
Set oRefAttr = oComponent.FindAttribute("Ref Designator")
If Not oRefAttr Is Nothing Then