I don't even see the need. Once you're a decent level the wildlife isn't tough at all. I actually had all 3 words for the whirlwind before I did unrelenting force =\
Yeah, it's an utterly pointless shout, especially when you have Animal Allegiance as well (which doesn't seem to do much either for me). I hope more shouts are released with expansions, because I'm actually quite disappointed at the shouts in the base game. I've still only got 1 word of Whirlwind Sprint though, I really should track down the rest.
Back on-topic, I understand why you'd want to get rid of the quest from your inventory, I have a couple of bugged quests that really irritate me, just sitting there doing nothing in my journal. I'm afraid I don't know what to suggest though

presumably you don't have a save from before you entered Ragnvald?