Login from Outlet and Admin Table

Try one of the available authentication libraries for CodeIgniter, like "Ion_auth" or "Community_auth". It will save a lot of time, and you will have better security.
Besides that, learn how to avoid repeating code.
E.g. the part where you determine if the user is a staff member or a customer can be way shorter:

PHP Code:

if ($staff->num_rows() > 0) {
  $data = $staff->row_array();
  $this->session->set_userdata('login', TRUE);
  $this->session->set_userdata('akses',$data['level');
  $this->session->set_userdata('ses_id', $data['username']);
  $this->session->set_userdata('ses-name', $data['name']);
  redirect('dashboard');
}
else {
     ...
}