You can manage certain aspects of your cPanel account in this client area.
After logging in to your account here, under Services > My Services, click on the row where you see your domain/website. Do not click directly on your domain/website or else you will navigate to it.
You'll find your quota and shortcuts to cPanel there.
You can also upgrade/downgrade your account and even cancel it by clicking on the appropriate buttons on the left (in desktop view).