You can use System Manager to delete a subnet when you no longer require the subnet and you want to reallocate the IP addresses that were assigned to the subnet.
The subnet that you want to delete must not have any LIFs that are using the IP addresses from the subnet.
You cannot use System Manager to delete subnets in the Cluster IPspace. You must use the command-line interface (CLI) instead.
Click Network > Subnets.
Select the subnet that you want to delete, and then click Delete.
Select the confirmation check box, and then click Delete.