As a reseller you have the ability to create hosting accounts and host them on your package.
Unlike end-user packages, we do not have the ability to resend the control panel details for these accounts you created. As the reseller, you would need to keep a record of the usernames and passwords you set for your customers.
You are able to change the password to these accounts within your WHM though.
To do this you would need to be logged in. Once you are logged in, search for "list accounts" in the quick search section found on the top left corner:
Once you click on the List Accounts option, search for the domain in question and "collapse" the options next to it.
You would notice that there is an option to change the password. Once you entered the new password then click on "Change" to complete the request.