Tada:
// Get input cookie object
$inputCookie = JFactory::getApplication()->input->cookie;
// Get cookie data
$value = $inputCookie->get($name = 'myCookie', $defaultValue = null);
// Check that cookie exists
$cookieExists = ($value === null);
// Set cookie data
$inputCookie->set($name = 'myCookie', $value = '123', $expire = 0);
// Remove cookie
$inputCookie->set('myCookie', null, time() - 1);