[I accidentally chose to be a guard instead of warrior?]

I wasn't paying attention and chose the wrong class.

 

I read in another forum that if you lower yourself back down to level 19 (which I just did) you are reverted back to being a fighter and can re-do the quest,

 

I am level 19 and it says I am still a guard and not a fighter. I don't want to have to start over. What can I do to get reverted back to a fighter?

 

Thanks so much to any answers.