eliminar todos los registros de la tabla
DELETE FROM table_name;
cómo eliminar fila en sql
delete from TableName where condition;
delete from scrumteam where firstname='Jack';
delete from scrumteam where JobTitle='SDET';
eliminar consulta
public function deletedata(){
$this->db->where('id', 2);
$this->db->delete('table_name');
}