Assume you're swapping the seat cover for a pillion seat? If so you'll need a seat with the plastic lock housing included- on the 2015 model at least, you can't remove the housing off the cover to install in a seat as it's all moulded in.
If you've got that, on the cover, remove the two bolts from the frame that holds the locking arm in, and remove the arm. Looking at the cylinder from from the underneath you should see a small metal tab that retains the cylinder in the housing. It's sprung, so use a very small screwdriver and push the tab in towards the lock cylinder. That should allow the cylinder to slide out (upwards if I recall correctly).
If you've got a cylinder that matches your key, then just install it in the seat, fit the arm and bolt the frame on, job done. If your cylinder doesn't match the key, you can still re-code it by swapping around the sliders, if you're lucky you won't need to buy any extras. It's not hard to do. On mine I only matched four sliders but figured that's still enough security for a seat.