After setting up the Custom Domain you can stop the .newzenler.com URL from appearing in the browser or to your users. This way your users will only see your custom domain name in the browser address bar.
eg. your-site.newzenler.com will be changed to www.your-site.com
To do this you have to set the Custom Domain as Primary.
The steps to set the Custom Domain as Primary are as follows:
1. Log in to your New Zenler school.
2. On the admin page go to Site -> Site Settings -> Custom Domain.
3. Turn on the toggle button, "Set as Primary".
4. Click on the OK button on the form "Are You Sure you would like to set this as your Primary domain?"