To change the addon or subdomain root folder:
Log into cPanel.
In the "Domains" section, click the Addon Domains or Subdomains icon, depending on which you'd like to modify:
By default, addon domains and subdomains use folders beneath the public_html folder - thus, the root directory for an addon domain named testdomain.com would by default be public_html/testdomain.com.
In the Modify a Domain section at the bottom of the page, click the pencil icon next to the current document root for the domain you wish to modify:
In the new opened window, enter the new document root and click Change: