If you want to remove only the installed binaries without the configuration use :
If you want to remove the installed binaries as well the configuration made within the program use :
sudo apt-get remove kopote
You can also try Gyachi available in this PPA : https://launchpad.net/~loell/+archive/ppa
sudo apt-get purge kopete
Moderator : Please add this message to my previous reply. Thanks.
More information can be found at :
Howto: Gyachi - Yahoo! messenger, Webcam, room voice chat, photo sharing - Ubuntu Forums