The phone is running:

SM-G390F

Android version : 7.0
Baseband version: G390FXXU1AQI2
Build number    : NRD90M.G390FXXU1AQI3

Root Device

• Download Boot & Recovery image from CF-Auto-Root for this device: ​https://desktop.firmware.mobi/device:289/firmware:13540
• Enable 'OEM Unlocking' in 'Settings -> Developer options'
• Reset device to factory default
• Put device in Download Mode by Powering it while holding down this keys: Power + Volume Down + Home.
• Retrieve PIT or download attached file sudo /usr/local/bin/heimdall download-pit --output SM-G390F.pit
• Use Heimdall to install new images: sudo /usr/local/bin/heimdall flash --pit SM-G390F.pit --RECOVERY recovery.img --CACHE cache.img
• Reboot phone and rooting will be done automatically

Removing factory applications

 $ adb shell
 $ su
 $ mount -o rw,remount /system
 $ rm -R /system/app/application-to-be-removed
 $ rm -R /system/priv-app/application-to-be-removed

file:/system is read-only be default. use mount -o rw,remount /system to make it writable.

Original firmware

Can be found at ​http://live.samsung-updates.com/index.php?device=SM-G390F