To Login to your cPanel from your ClientArea, there are few things you need to do.
1) Login to your ClientArea.
2) Go to Service Area either from home dashboard, click on services from the white space.
The second way is to go to my account , located at top right section of your ClienArea, then select the service from the dropdown menu.
3) Select Your Hosting Service,
4) At the Left corner of your Hosting Dashboard, you will see all the options required for Login into the cPanel, Just click on the Login to cPanel link, and you will be taken directly to cPanel.