"App" stuck in Recents

Hey,

for about two months now I've had an app stuck in recents, and no matter what I do it won't go away. It's basically a website I opened from a google search. I've deleted and reinstalled Google Now, the phone has been upgraded from 5.1 to 5.1.1 in between, restarting, nothing seems to do the trick. I've been googling the problem without success so far.

Has anyone seen anything like this before? I'd appreciate suggestions.
Here's a screenshot: http://i.imgur.com/lJGYVHj.png

Nexus 5, stock 5.1.1

Anyway to access multi window without recents button.

I liked how it used to be by pressing and holding the back button to bring up the multi window side panel. I can't seem to find anyway to bring it up. Please don't tell me using the recents button is the only way. I liked how on the note 4 you could just press one of the multi window apps and it would open up as a pop up.

Sent from my SM-T807P using XDA Free mobile app