Just removed the rear seat cushion in my 2015, to install a seat cover.
What a pain!!
There are several problems.
1 - Wheras the 2012 rear seat had some rigidity, the 2015 "rear cushion" has no real frame strength.
2 - The clips hold with tremendous force.
3 - the metal loops are wrapped with cloth adhesive tape. This may ruin whatever chance the clip had of releasing.
4 - there is no way to get any kind of tool involved to press in on the tabs that hold the clips in place
It's difficult to remove without damaging the clips, the holes they fit into, or the seat itself.
Here's a picture of the underside of the seat. The receiving clip is still attached to the metal loop It just wouldn't let go. Now that it's exposed I can push in the tabs to remove it.
Here you can see the frame hole where the clip is supposed to reside. You can see the hole is distorted a bit. That's how hard I had to pull to get a release. Next to the hole is the clip from the passenger side, which finally did let go of the metal loop after some wrasslin'.
There's no way to get at the clips to make them release. On the driver's side I was able to get the thing to pop out by grabbing both the front of the seat directly in front of the clip, and also the rear of the seat and pulling up from both ends finally got it. It took a LOT of force. I'm probably going to have to bend the cushion back into shape a bit and also have to tap that hole back into shape.
On the passenger side I finally got it out by kneeling outside the car, snaking my arm along the top of that ridge, wrapping my hand around where the clip was and then lever-ing it out.
Were I to try this again I think I'd tie a rope into a noose, get it fished around the clip, cinch it down and the pull up with that from the front side of the seat. This would concentrate the force right at the clip interface. There just isn't enough strength in the seat itself to transmit force effectively.
Dammit Nissan, why did you make it so hard? People do want to put on seat covers occasionally!