So, I know of no way to abandon a quest once you have it. When I talk to Farkas he just tells me "You already have a job, now get to it." None of the other leaders of the Companions will give me work because I have this [censored] bugged quest.
So, I have now sunk over 25 hours into this charachter. I guess it's start over or wait for the people at Bethesda to stop patting themselves on the back for thier "GOTY" and counting thier money and fix some damn major bugs. What a stupid waste.