how to get rid of light desktop manager entry in ubuntu greeter

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http://askubuntu.com – Got "light desktop manager" entry in ubuntu greeter for some strange reason and can't get rid of it. As the current OS is Ubunu 13.10 the way to configure the lightdm greeter is rather strange, can't find any solution in greeter configs. More annoying thing is that Mr.LDM seems to have password very hard to guess so I can't login to this "account". Can you help me to find source of this problem and find the solution? (HowTos)