If you're not rooted then there's no way to do so. If you are rooted however, it's pretty easy. Reply to me if you want to know how.
THis only works if you are rooted, as I stated before.
I'm pretty sure you have to this:
With root access,
1. go to /system/fonts
2. rename NotoColorEmoji.ttf to anythign you'd like(lika a backup of it)
3. rename AndroidEmoji.ttf to NotoColorEmoji.tff
4. reboot
That SHOULD do the trick. I'm more used to changing the emoji to apple's Emoji to match them with Whatsapp.
Grab AppleColorEmoji.ttf and place it into /system/fonts/
Set /system/fonts/AppleColorEmoji.ttf to have permissions 644 (rw-r--r--) and owner:root group:root.
then do the process mentioned above, but use AppleColorEmoji instead of AndroidEmoji.
Also, right now there's no reason not to root, since towelroot doesn't trip the Knox Counter. That way, you keep your warranty and also have the benefits of a rooted phone. (Don't quote me on that, that's at least what I read )