brew cask: howto uninstall an Application

I tried, while I am in /opt/homebrew-cask/Caskroom

$ for i in *; do brew cask uninstall $i; done
Error: appcleaner is not installed
Error: avidemux is not installed
Error: eclipse-ide is not installed
Error: flash is not installed
Error: silverlight is not installed
Error: thunderbird is not installed
Error: vlc is not installed

He uninstalled several apps, but those not. Why?

$ brew cask list
appcleaner    avidemux      eclipse-ide   flash     silverlight   thunderbird   vlc

$ pwd
/opt/homebrew-cask/Caskroom
$ ls
appcleaner  avidemux    eclipse-ide flash       silverlight thunderbird vlc
$ du -sh .
532M    .

Howto uninstall them properly? He didn't uninstall because updated without brew cask?

brew cask uninstall --force

This will remove all versions of a Cask.

And unless you want the preferences lying around you can also do:

brew cask zap [your cask]