Do the following to create an account in WHM
- Log in to your WHM.
- Click on the Account Functions icon.
- Click on the Create a New Account sub-icon.
- Fill out the new domain information which includes the domain name, username, password and contact email for the new account.
- Choose a hosting package.
- Click the Create button.
If you want to give them access to WHM as well, you can make them reseller.
4,1 Under Reseller Settings, check Make the account a Reseller.
4.2 (Optional) You can check Make the account own itself so the owner can modify the account.
Your reseller customer will now be able to access WHM and login with the cPanel username and password you just created. You can visit the following URL to choose what privileges you want to assign to these resellers.
https://docs.cpanel.net/whm/resellers/edit-reseller-nameservers-and-privileges/
If you need any further help, do not hesitate to reach me out.