HP-UX IPv6 Transport Administrator's Guide for TOUR 2.0 (April 2004, rev 2)

IPv6 Addressing and Concepts
Stateless Address Autoconfiguration
Chapter 6 65
The primary interface (for example, lan1) can then be removed from the
system with the ifconfig command, as in the following example:
ifconfig lan1 inet6 unplumb
A loopback interface does not have a hardware device associated with it.
The name of the loopback interface is lo0. A loopback interface is
automatically created by the system. You cannot delete it.