How to remove quest item from back?

[Shiraishi An]

I was messing around and took the hatched dragon from my friends quest for luls. I already finished the quest and now I have that bag on my back and can't find out how to get rid of it. Anyone know how to fix this? Or am I gonna get smacked by Karma for being a poop troll. :C

[Tom is a Door]

just drag it outside of the inventory window, just click and drag to the right till it is out of the bag window prompt thingy

[Shiraishi An]

It's not an item that shows up in your inventory. It disappeared by itself over time.