I have untracked this multiple times on my main (a level 60, for that matter) and it keeps re-asserting itself as my active quest. I would like to hold off until I decide who to use it on but at this point I almost want to just use it to get rid of it.
I’m sorry but I’m at my wit’s ends if you guys could do just one thing without causing trouble I would be amazed.
It seems to happen when I transition into a differently named area.
I would like to know how to disable this, too. It’s the most annoying thing in the history of the world. I’ve disabled auto-pin, but it keeps re-pinning itself anyway.
I’m having this problem too (on Xbox). Would love to be able to permanently untrack it.
This was so frustrating that I logged into a different character just to take the boost (that I have ZERO interest in ever using) but then when I went back to the character I actually want to play, THE QUEST IS STILL THERE!
Beyond annoying, I just quit, gonna play something else.
I am having the same problem. The Welcome Back Booster quest continually replaces the quest I am doing in the tracking window. It’s very annoying.
if you own the expansion you can claim 2 boosts, maybe that’s it?
quests auto-pinning themselves is absolutely infuriating EVERY. SINGLE. TIME. i have hated it since the first time i experienced it. having the “new quest” icon on your journal and unable to remove it on many of these quests makes it that much worse. just get rid of this irritating “feature” already. you have popups on launch for events, that’s fine. if people miss out because they don’t look at that, that’s on them.
i guess what i’m saying is stop pandering to idiots, they will find ways to screw something up regardless, it’s just what they do…
Ah I didn’t realise. Guess I need to waste more time and ruin another character with an unwanted boost so I can finally get rid of the quest.
fixed it for ya 
Pretty sure this is it. I did it on two characters and the quest is now gone.