Disabling a service here means, stopping the service right now and also disabling it from restarting even after reboots.
Assuming the name of the service is "my_service" then the following command will completely disable the service "my_service":
whmapi1 configureservice service=my_service enabled=0 monitored=0 && systemctl disable my_service --now
For example, the following command will completely disable Apache (service name = httpd) on the server:
whmapi1 configureservice service=httpd enabled=0 monitored=0 && systemctl disable httpd --now