netiucv.c1b7ef <bus ID of the IUCV device>: The IUCV device is connected to <remote z/VM user ID> and cannot be removed
Explanation
Removing a connection failed because the interface is active with a peer
interface on a remote z/VM guest virtual machine.
User response
Deactivate the interface with "ifconfig down" or an equivalent command;
then try again to remove the interface.