So this seems to be a bit confusing to you! So here I am to save the day! (hopefully).

You are not locked into the quest until you have COMPLETED IT. You do not complete it till you return to the mob giver AFTER seeing Norrix. You can ABANDON <quest name> before you COMPLETE the quest. After completion you're locked.

Hope this helps!

Penned by my hand on the 23rd of Artificium, in the year 60 AM.