public void RemoveStandaloneTables( 
   IEnumerable<StandaloneTable> tables
)

{
    //get the first group layer that has at least one table
    var grp_layer = MapView.Active.Map.GetLayersAsFlattenedList()
      .OfType<GroupLayer>().First(g => g.StandaloneTables.Count > 0);

    //Note: Run within a QueuedTask
    //get the tables from the map container
    var tables = map.GetStandaloneTablesAsFlattenedList();
    //delete the first...
    if (tables.Count() > 0)
    {
        map.RemoveStandaloneTable(tables.First());
        //or delete all of them
        map.RemoveStandaloneTables(tables);
    }

    //delete a table from a group layer
    //assumes it has at least one table...
    grp_layer.RemoveStandaloneTable(grp_layer.StandaloneTables.First());
}