format and install new OS to get rid of viruses I have an android phone (my uncle's) that is full of viruses that display adds and reinstall themselves I'm guessing
there is no important/needed data on the phone

I tried factory reset, after used Dr Web to find viruses, and to root the phone (Kingo ROOT) in order to be able to remove some of them, 2 files identified by drweb couldn't be removed even though the phone was rooted because they were system files (priv-app/baseservice.apk and another one), I renamed them instead.

all this ^ didn't helped completely, they appear again somehow, so would like to format and clean install a new OS

is there a easy way to do that ?
my guess is I need some program on my pc (windows7) for this and connect the phone using usb and run some commands

the device is a fake galaxy S6, Android 5.0.2 kernel version 3.10.61
Things you can do:


Downgrade to your stock ROM and install a good antivirus and run a complete device scan because some of them are powerful enough to remove viruses from system files in priveledged user mode.
Install Ubuntu Touch instead of android as shown in this guide. The guide is actually primarily for nexus devices but you can make it work for Galaxy S6 by finding the stock ROM yourself and other stuff for the S6 yourself instead of following the links given in the guide which are for nexus devices.
If that doesn't work and you are unable to install Ubuntu touch for some reason try this.