Yeah I know where to get the quest to cleanse it but my problem is that the NPC supposed to give me it doesn't give me any options to take a questlol. Your title made me Think "Fifty Shades of Green"... a BDSM sequel to the Lusty Argonian Maid. But to answer your question, I found this info on another site:
"If you're stuck on the step to cleanse Dread Vullain, it's because you're missing a secondary quest. The quest giver can be found at 36, 27, northwest of the town. I've uploaded a screenshot with the map location, in case Esohead ever gets around to approving screenshots (hint hint).
Go there, pick up the quest, and look around for Indaenir. He'll show up and get you back on track. Complete the new quest, and you'll cleanse Dread Vullain in the process. I'm being intentionally vague on details, since the game is so new. Don't worry, it'll be obvious once you get the secondary quest!"
If that doesn't work, try abandoning the quest and trying again?
Good Luck!