Introduction
This guide will tell you how to change a site's IP address in WHM.
Procedure
1) Login to WHM as root
2) Navigate to Home -> Account Functions -> Change Site's IP Address
3) Click on a user/domain and then click the Change button
4) Click the New Address dropdown menu
5) Click the IP address you would like to change to from the list and then click the Change button
Official Documentation:
https://docs.cpanel.net/whm/account-functions/change-site-ip-address/