DNSOnly servers do not provide the Change Root Password option in WHM. Since DNSOnly servers provide only basic DNS service, there is no need for this function, as it changes the password for multiple services on regular cPanel servers.
To change the root password on a DNSOnly server, connect to the server via SSH, then run the
passwd command as the root user:
[root@server ~]# passwd
Changing password for user root.
Retype new password:
passwd: all authentication tokens updated successfully.