Codeigniter app bug: login credential are remembered even if remember me is not checked-Twitter bootstrap

I am working on an online newspaper/blogging application with CodeIgniter 3.1.8 and Twitter Bootstrap 4. The application, of course, has a login and registration system.

I am currently working on adding a "remember me" functionality to the login form.

In applicationviewsauthlogin.php I have:

<?php echo form_open(base_url('login/login')); ?>
  <div class="form-group <?php if(form_error('email')) echo 'has-error';?>">
    <input type="text" name="email" id="email" value="<?php if(isset($_COOKIE['userEmail'])) { echo $_COOKIE['userEmail']; } ?>" class="form-control" placeholder="Email">
    <?php if(form_error('email')) echo form_error('email'); ?> 
  </div>
  <div class="form-group <?php if(form_error('password')) echo 'has-error';?>">
    <input type="password" name="password" id="password" value="<?php if(isset($_COOKIE['userPassword'])) { echo $_COOKIE['userPassword']; } ?>" class="form-control" placeholder="Password"> 
    <?php if(form_error('password')) echo form_error('password'); ?> 
  </div>
  <div class="form-group remember-me">
    <input type="checkbox" name="remember_me" value="true" id="remember_me">
    <span class="text text-muted">Remember me</span>
  </div>
  <div class="form-group">
    <input type="submit" value="Login" class="btn btn-block btn-md btn-success">
  </div>
<?php echo form_close(); ?>

In the controller (applicationcontrollersLogin.php), I have:

public function login() {  
    $this->form_validation->set_rules('email', 'Email', 'required|trim|valid_email');
    $this->form_validation->set_rules('password', 'Password', 'required|trim');
    $this->form_validation->set_error_delimiters('<p class="error-message">', '</p>');
    if ($this->form_validation->run()) {
      $email = $this->input->post('email');
      $password = $this->input->post('password');
    
      $this->load->model('Usermodel');
      $current_user = $this->Usermodel->user_login($email, $password);
        // If we find a user
      if ($current_user) {
        // If the user found is active
        if ($current_user->active == 1) {
          $this->session->set_userdata(
           array(
            'user_id' => $current_user->id,
            'user_email' => $current_user->email,
            'user_avatar' => $current_user->avatar,
            'user_first_name' => $current_user->first_name,
            'user_is_admin' => $current_user->is_admin,
            'user_active' => $current_user->active,
            'is_logged_in' => TRUE
            )
           );

           // Remember me
           if (!empty($this->input->post('remember_me'))) {
            setcookie ('userEmail', $email, time() + (7 * 24 * 3600));  
            setcookie ('userPassword', $password,  time() + (7 * 24 * 3600));
           } else {
            setcookie ('userEmail', ''); 
            setcookie ('userPassword','');
          }
          
          // After login, display flash message
          $this->session->set_flashdata('user_signin', 'You have signed in');
          //and redirect to the posts page
          redirect('/dashboard');
        } else {
          // If the user found is NOT active
          $this->session->set_flashdata("login_failure_activation", "Your account has not been activated yet.");
          redirect('login'); 
        }
      } else {
        // If we do NOT find a user
        $this->session->set_flashdata("login_failure_incorrect", "Incorrect email or password.");
        redirect('login'); 
      }
    }
    else {
      $this->index();
    }
}

The problem

For a reason I have been unable to spot, even when the remember_me checkbox is NOT checked, the login credentials are still remembered.

UPDATE

I went to applicationconfigconfig.php and replaced $config['sess_expiration'] = 7200 width:

$config['sess_expiration'] = 0;

As a result, the remembering does not happen anymore.

Where is my mistake?