SSH is blocked by default for the root user.

To enable the root access
Edit the file /etc/ssh/sshd_config
You need to change the value PermitRootLogin to Yes
Needs a reboot

To open the Firewall Ports on your ESX Host:

To allow access to ESX Server for a service or management agent
1  Log on to the VI Client and select the server from the inventory panel. 

The hardware configuration page for this server appears.
2  Click the Configuration tab and click Security Profile. 

Select the SSH Client and SSH Server checkbox and click OK.