Gray-scale

Hello,
Hello i have Samsung note 4
after the update in 2016 the gray scale no longer available
the gray scale was possible on power saving , with allowing all the other functions , it helped to save battery and also very relaxing for the eyes while now it is possible just on Ultra power saving , wonder if it possible to take the updates out , wish i did not update , it really misleading as it was one of the features of the phone and its out , do you know where we can write to the company or what to do