NSX-T appliances use systemd so: systemctl sshd start should do it.
Enable SSH and, if needed, allow root SSH login to the NSX Manager command line.
By default, these options are disabled for security reasons.
I was trying to get the same done and finally got it done, here is what I have followed.
1) Opened the NSX-T Manager VM console and logged as root.
2) Edit /etc/ssh/sshd_config in vim editor by modifying the following line,
Change PermitRootLogin to yes
Change StrictModes to no
3) Restart the ssh service