Throughout this tutorial, you'll see how to review and analyse the disk space usage of your cPanel hosting account. 
Whether you have a VPS, Dedicated with cPanel or a Shared Web Hosting account this guide will provide actionnable knowledge for you to assess the current disk usage of a given account. 

1) First login to the concerned cPanel account and click on Disk Usage. 

2) Wait for the disk report to be generated which will reflect the details of  your Disk Usage for you to investigate. 

The report includes two parts. The first lists all the usages (Email / MySQL / Total Space Use by Files / Structural Folders).  Each items are clickable which would lead you to the concerned place allowing you to have a better granularity of reporting.

The second part includes the nested directory structure with collapsable directory to exactly pin point where the space is being used. 

That's it, you know how to use the Disk Usage feature of cPanel to review and analyse where it is being consumed.