1. Go to WHM > Packages > Add a Package.
2. Fill out the values you want for your hosting plan. This includes the Package Name.  Common settings include "10" for Quota, "100" for Bandwidth, and "unlimited" for everything else.
3. Once done, click the Add button at the bottom of the page.
4. Now go to WHM > Account Functions > Upgrade/Downgrade an Account.
5. Select your domain name and click the Modify button.
6. Select the name of your new plan and click the Upgrade/Downgrade button.
7. All done!

Package Limitations You Can Set

Packages define the limitations of cPanel accounts that you create. The limitations which you may set are as follows:

• Quota (MB) – Disk space in megabytes available for the cPanel account.
• Bandwidth (MB) – Data transfer in megabytes available for the cPanel account.
• Max FTP Accounts
• Max Email Accounts
• Max Email Lists
• Max Databases
• Max Sub Domains
• Max Parked Domains
• Max Addon Domains