In principle, HA-SEAs are removed just like a simple SEA, using the command “vios rmdev“. You just have to make sure that both SEAs are removed.

To avoid a failover, the backup SEA should be removed first.

In our case the Backup SEA is ent41 on ms05-vio2:

$ vios rmdev -d ms05-vio2 ent41
$

The primary SEA ent43 on ms05-vio1 can be removed afterwards:

$ vios rmdev -d ms05-vio1 ent43
$

The client LPARs immediately lose access to the external network for the VLAN IDs supported by the deleted SEAs!