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);
var map = MapView.Active.Map;//assumes non-null

QueuedTask.Run(() =>
{
  //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());
});