This article will allow you to redirect a Sub domain to another page.
Log into cPanel with your credentials
In the Domains section, left click the "Subdomains" icon.
Under Modify a Subdomain, left click the "Manage Redirection" link to the right of the Subdomain you wish to redirect.
In the text box, type the URL to which you would like visitors to be redirected if they go to the subdomain (e.g. http://domain.com/optional-stuff).
Then left click "Save"
When you visit the subdomain, you will be now redirected to the specified page.