apagar todos os registos da tabela
DELETE FROM table_name;
como apagar a linha em sql
delete from TableName where condition;
delete from scrumteam where firstname='Jack';
delete from scrumteam where JobTitle='SDET';
apagar a pesquisa
public function deletedata(){
$this->db->where('id', 2);
$this->db->delete('table_name');
}