[1MciprianM]

The phone is not rooted.

[Bosbouer]

If you activated it through Android SDK then you should be able to deactivate there again. It is not available by default on the N910F note 4

[1MciprianM]

I didn't write a program to activate it, nor did I install and used a program to activate it. The reason why I believe it's on is that after restart, when I look into the recent apps, all the apps that I had before are there. And for some apps that were on before the restart, they get back on again and show up on the screen. So it's either a default setting that comes with this version of android, either an option that I could deactivate. But I haven't found such an option yet.

[Bosbouer]

It's power and parcel of Android ram management. Unless you clear your last used apps before you shut down that list will reappear.You could have a look in Dev options(you need to activate it from settings about device and tap on build 7 times). Maybe you can change ram management there