Before removing motherboard, we have to remove LCD screen. You can see more details on Samsung Galaxy Note 4 LCD screen replacement.
If just removing the rear camera it is not necessary to remove the LCD from the assembly. simply unscrew the one screw located on the left side of the motherboard and disconnect flex cables with a plastic spudger, keeping in mind the two connections underneath the board where the LCD connects. You run less risk of damage to the display this way.