Just remove it manually:
Code:
# rm /etc/apt/sources.list.d/<name of repository>
It will probably be called "moorkai.list" or something (I don't use Mint)...
EDIT: Actually, it may be added directly to
/etc/apt/sources.list -- look for these lines and comment them out (put a "#" symbol, without the quotation marks, at the start of the line):
Code:
deb http://ppa.launchpad.net/moorkai/cinnamon/ubuntu utopic main
deb-src http://ppa.launchpad.net/moorkai/cinnamon/ubuntu utopic main
Make sure you use `apt-get update` after changing your sources.