During my CapacityIQ hands-on I reinstalled my CapacityIQ VA. The problem is that I have forgotten to uninstall / unregister the appliance inside vCenter server first.
After reinstallation I wanted to register the CapacityIQ appliance again in vCenter, which failed with the following error: "Another CIQ is registered to VC. Unregister it or register with force flag from CLI."
Normally you are able to unregister the appliance inside it's CLI. For it you have to log on as user "ciqadmin" and simply run the command "ciq-admin unregister". But without the origin VA this is not possible anymore 
As stated by the message above, there is also a possibility to force the registration of the CIQ appliance:
"ciq-admin register --vc-server <vc_server_ip> --force --user 'company_domain\username'
--password 'password_with_special_characters' "
Note: If you have issues with the hostname you should use the "--use-ip" parameter:
"ciq-admin register --vc-server <vc_server_ip> --use-ip
--force --user <vc_username> --password <vc_password>"
Afterwards the new CapacityIQ appliance was registered again with my vCenter!
