You can add and delete subnets for an IP block from the NSX Manager GUI.
- From a browser, log in to the NSX Manager at https://<nsx-manager-IP-address-or-domain-name>.
- Select DDI.
A list of the existing IP blocks is displayed.
- Click an IP block name
- Click the Subnets tab.
- Perform any of the following actions..
Add an IP block subnet
Delete one or more IP block subnets
Select one or more subnets and click DELETE.