This is the code I have in my Kiktart.kix

;Run script for removal of Winzip
If @USERID = schnellb
Call WinzipRemove.kix
EndIf

Then in my WinzipRemove.kix I have

If Exist($C:\Program Files\WinZip + '\WINZIP32.EXE')
Run $C:\Program Files\WinZip + '\WINZIP32.EXE /uninstallx'
EndIf

Is there anything else I need for this to work?