To change the origin to an existing zone follow the steps outlined below:
1. Log in to the Universal CDN Control Panel at ucdn.com.
2. Navigate to the My Zones tab located in the top left corner.
3. Click on the cogwheel icon 
next to the CDN zone which CNAME(s) will be changed.
4. Click on Main settings.
5. Determine the location of your files.
Limit Access Using a Secret Key