I have gone through this, but I don't see the alias IP. I think we have to put the alias IP here to remove. It's not already there for us to choose to remove :)
I have some doubt about the NIC device on my AIX box.
When using lsdev command
[root@xxx] / > lsdev -Cc adapter | grep en
ent0 Available 03-00 2-Port 10/100/1000 Base-TX PCI-Express...