保存后，Codeigniter会话数据会破坏

I am using session value in to my form set_value . I want destroy the set_value after the form successfully save

$vv=$this->session->userdata;
$reason=$vv['reason'];


<textarea id="present"  name="reason" class="form-control " required rows="6"> <?php echo set_value('reason',$reason); ?> </textarea>

Just use unset to Remove any session value.

unset($_SESSION['xyz']);

In-case of codeignitor, you can use:

$this->session->unset_userdata('xyz');