From your reseller WHM account, you can easily increase the disk quota for any of your customers’ cPanel accounts.
Here are the steps you’ll need to follow –
1. Log in to WHM (using http://domain/whm).
2. Under Account Function, you can see the tab Quota Modification.
3. Select the domain from your domain list and click on Modify.
4. There, you can modify the Quota limit.
5. Click on change. Now, the quota limit will be changed.
That’s how you can increase or change the disk space quota from WHM.