clearing cookie in js code example

Example 1: clearing cookie in js

document.cookie.split(";")
  .forEach(function(c) { 
  	document.cookie = c.replace(/^ +/, "").replace(/=.*/, "=;expires=" + new Date().toUTCString() + ";path=/"); });

Example 2: clearing cookie in js

cannot read property 'getCookieString' of undefined. How do I fix this? Trying to install an app