Was looking for this for a while and I found the solution in the Note edge forum posted by Skenderbeggar. Basically Samsung removed the option to hide or display the brightness slider, I personally don't use it and think it takes up a lot of space. This should work with all varients.

1. Get SQLite Editor (Does cost $. but you can use it for other things too)

2. Open it, and select the FILES column

3. Scroll to the DATA folder and open it

4. Scroll to the DATA folder within it and open it

5. Scroll to the COM.ANDROID.PROVIDERS.SETTINGS folder and open it

5. Open the DATABASES folder

6. Open the "settings.db "file

7. Click on the "system" file

8. Select "notification_panel_brightness_adjustment" (number 279 on my list)

9. Change the value from 1 to 0.

10. Save, close out and reboot.