No bro, you are not rooting your device.it is safe. No warrenty will be void.

First connect you phone with usb to any laptop or pc. Then switch off device.Then press and hold the volume up and power button both for 5 min till the samsung logo comes.You will enter in boot menu. There wipe the catch partition

First wipe the catch partition in boot menu and restart device.If problem is still presist then you have to reset you device

Which model?

Yes of course you can.