In this article, I will demonstrate how you can add and remove NTP servers from your NSX-T Manager.
List current configured NTP source(s)
Connect to the NSX-T Manager via SSH and log on with your admin credentials.

If you want to see the existing time configuration before you add or remove sources, run the following command to list the current configured NTP servers.
get ntp-server

Add a new NTP source
Add a new NTP source by running the following command:
set ntp-server ntp.uniserver.nl
get ntp-server
The new NTP server is now added to the list of available NTP sources.

Remove existing entries from the NTP source list.
If you want to remove existing NTP entries from the NTP source list, run the following commands:
del ntp-server 192.168.200.101
del ntp-server 192.168.200.102
Run the following command to list the currently configured NTP servers.
get ntp-server

As highlighted in the screenshot of the CLI, the new time server is used.
A full list of NSX-CLI commands can be found here:
NSX-T Command-Line Interface Reference for NSX-T Data Center 3.0.0