Remove pre installed app through adb

[Android Question]

To begin with I am a Commerce student and completly new to this process..
Please please help me bro.
I have just purchase Iball Andi 4di+ device Cortex A7 dual core running JB 4.2.2. Naturally i wont root it straight away to avoid voiding warranty.
It had whatsapp pre-installed which i want to replace with whatsapp plus which cant b done unless i uninstall whatsapp..
Though I have used android phones previously m completely new to all these stuffs and rooting too..I have android sdk in my pc. And tried the adb way to remove whatsapp with commands-
adb devices
adb shell
cd system/app
ls
rm whatsapp.apk
But it showed failed on

 

[scary alien]

Hello and welcome to our AndroidForums!

Unfortunately, I'm 99.99% certainly you'll have to be rooted in order to remove or rename your pre-installed app from /system/app since that's typically a protected area.

You're on the right track as far as commands go, but you'll need to have root privileges before you'll be able to remount the /system partition in read-write mode and then do the rename / remove, etc. on it.

(I don't have or know the rooting procedure for your device--you'll have to find that elsewhere I'm afraid)

Best of luck!