How to delete Via in layout?

I draw my layout. When I use the function deleteAllObjectsInLayout( cvid ) to delete the layout, all instances and metals are deleted except the Vias I created. the function is defined below, How should I modify my code for deleting Vias? Thank you! procedure(deleteAllObjectsInLayout( cvid ) let((propName inst) dbDeleteAllNet( cvid ) foreach( inst cvid~>instances dbDeleteObject( inst )) foreach( inst getSGq( cvid shapes ) dbDeleteObject( inst )) t);end let );end procedure