adb shell

su
mount -o rw,remount /system

[100% necessary]
rm /system/priv-app/Launcher3/Launcher3.apk
rm /system/priv-app/SystemUI/SystemUI.apk
rm /system/priv-app/FactoryTest/FactoryTest.apk
*****rm /system/priv-app/UpgradeUI/UpgradeUI.apk

[other packages]
rm /system/priv-app/AkuvoxPhone/AkuvoxPhone.apk
rm /system/priv-app/rtspd/rtspd.apk
rm /system/priv-app/LogService/LogService.apk
rm /system/priv-app/FactoryTest/FactoryTest.apk
rm /system/priv-app/FactoryTest-IT83/FactoryTest-IT83.apk
rm /system/priv-app/FactoryTest-C315/FactoryTest-C315.apk
rm /system/priv-app/AppManager/AppManager.apk
rm /system/priv-app/PMonitor/PMonitor.apk
rm /system/priv-app/Explorermini/Explorermini.apk

rm /system/priv-app/AkFace/AkFace.apk
rm /system/priv-app/SystemUI/SystemUI.apk

dpm set-device-owner net.alphamedia.AlphaTouch_ATxM/net.alphamedia.AlphaTouch_ATxM.DeviceAdminReceiver