Every Web Application you install from cpanel has an entry listed under My Applications.
Use this interface to find the link to administer the site, change any of the settings (for example the login username/password), make a copy of the site elsewhere, and delete it.
Each site listed here is represented by a screenshot (this may not reflect the most recent changes).
The first link provides the public view while the second link is the one you use to manage the site (for some apps like WordPress the login will be done for you via this link, for other apps, you will need to know your username and password).
What if you forget the password? Look for the wrench icon on the right side tools. This lets you change any of the settings entered when first installing the app, and allows you to see/change ones like the admin password.
One of the most powerful tools is the third icon, the clone tool. This makes it possible for you to make a duplicate of the site, including all of the settings and database, in another location of your domain. This might be something you use if you create a version of your site in a sandbox subdomain (see the Building a Domain Sandbox kit), and then want to move it to a more public location (another subdomain, at your main domain, or a directory in either location).
The “x” button is used to delete an application. Why delete? Perhaps it did not work out for you. You might also have to delete experimental sites for accounts on StateU because these free trial accounts have limited number of databases you can create and disk space allowances.
As you create your sites from these kits, explore them as listed under My Applications in cpanel so you know how to manage them.
Example for "Managing Installed Web Apps":