If you've joined a clan, or bloodline, and have done everything you wanted to but are done with them, there is an odd process to take.

First, make your way to Suran. From there, travel northeast until you reach the daedric ruin- Bal Fel.

Inside, there will be a door leading you to a narrow path. Continue along this narrow path, beyond the lava to find a woman and a shrine. Talk to the shrine of Maclath. He will tell you of his problems with his daughter, and wants you to slay her. She and her frost Atronach friend are located in Dubdilla. Dubdilla is south of Vos. Make your way there and slay the two. If you put a spell of Mark on the shrine, recall there, if not, you're in for a long hike back.

Talk to the shrine to regain your humanity.