Hello Alex,
At first please make sure the water has been drained from the loop. You can refer to follows video to see how to drain the water.
And then remove the tube and radiator of the water cooling kit, and go on removing the mirror plate of the case, and then turn off the screw and take off the distro plate carefully.
Any questions, feel free to contact us.
https://www.youtube.com/watch?v=K7ecpBJ93rg