How to Clear Form Values in Drupal?

function my_module_my_form($form_state) {
  $form['name'] = array(
    '#type' => 'fieldset',
    '#title' => t('Name'),
    '#collapsible' => TRUE,
    '#collapsed' => FALSE,
  );
 
  // Removes the #required property and
  // uses the validation function instead.
  $form['name']['first'] = array(
    '#type' => 'textfield',
    '#title' => t('First name'),
    '#default_value' => "First name",
    '#description' => "Please enter your first name.",
    '#size' => 20,
    '#maxlength' => 20,
  );
 
  $form['submit'] = array(
    '#type' => 'submit',
    '#value' => 'Submit',
  );

  // Adds a new button to clear the form. The #validate property
  // directs the form to use a new validation handler function in place
  // of the default.
  $form['clear'] = array(
    '#type' => 'submit',
    '#value' => 'Reset form',
    '#validate' => array('my_module_my_form_clear'),
  );
 
  return $form;
}

// This is the new validation handler for our Reset button. Setting
// the $form_state['rebuild'] value to TRUE, clears the form and also
// skips the submit handler.function my_module_my_form_clear($form, &$form_state) {
    $form_state['rebuild'] = TRUE;
}