Returning Public IP Addresses to Service Providers

To return one or more IP addresses to the service provider:

Start at the Addresses page for the subscriber.
In the Public IP Addresses table, click in the small box in the last column for each address that you want to return.
If an enabled NAT rule is using an address, the box for that address is dimmed, and you cannot release that address until you disable or delete the NAT rule listed in the Used By field.
Click Release.