Close Demat account

Guys, Over a period of time, i have accumulated a few demat accounts in different places. I want to consolidate and close a few. I definitely want to close Geojit & Kotak. Have not used them for a long while and may have some AMC's pending. Kotak just charges me some 2400 annual for some crappy reccomendations, i have not been able to cancel it. very irritating that is. Anyways, what should i keep in mind before closing them. Both have some legacy defunct useless shares. one has Core Education and other has Kingfisher Airlines. What all to keep in mind ? Cheers, dhvaar