1) Log into WHM.
2) Scroll down and click on on the List Accounts button located under the Account Information section.
3) Once on the Account List page, simply click the plus sign [+] located in the front of the account you want to update.
4) In the expanded panel click on the Change Plan button.
5) Select the new plan you want to assign to the account and click Upgrade/Downgrade to save the changes.
Please make sure you have multiple hosting packages created first, you can easily create a new hosting package by following the instructions provided in this article.
6) The account’s package has been changed successfully. You’ll see a list of all the changes WHM has made below.
7) If you go back to the List Account section you will see the new plan assigned to the account.