I've looked everywhere and have used every mod that I can find with regards to removing "essential" flags from NPCs so that I can kill them. Does anyone know of a mod like this that actually works? I have tried to create one myself using the creation kit on Steam, but unticking "essential" on npcs just doesn't work.

Here are a few I've found. Maybe one of these will work:

http://skyrim.nexusmods.com/mods/25137 by PrinceShroob

http://skyrim.nexusmods.com/mods/16093 by ThanatosNihil

http://skyrim.nexusmods.com/mods/8783 by Strategy Master

http://skyrim.nexusmods.com/mods/8415 by FlapjacksNsyrup

http://skyrim.nexusmods.com/mods/8170 by Yoshanuikabundi

http://http://skyrim.nexusmods.com/mods/2570 by vertex23