These steps will uninstall system apps from a un-rooted device. All links open in new tab.

Tested with:

• Lenovo S660
• Xiaomi RedMi Note 3 Pro
• Samsung Galaxy J3
• Lenovo Yoga Tab3

Disclaimer: Uninstalling system apps might make your device unusable. If you choose to do it, you’re doing it on your own risk! 

Prerequisites:

• USB drivers for your device. You can install them from here: universal USB drivers (check the instruction provided there)
• ADB binary for your particular OS (Windows, Mac, Linux). Extract the zip file. For Windows I use Minimal ADB and Fastboot (direct link).
• Install App Inspector. This is needed to get the app names

 

Connect the phone:

• If Developer Options is not visible on your phone, go to Settings and tap on About. Tap on android version 7 times to make it visible.
• Now, enter Developer Options and find USB Debugging. Enable it.
• Plug your phone into the computer and from the notification panel change from Charge only mode to File transfer (MTP) mode or Media device (MTP). On some devices you need to check USB debug mode (ADB) too
• On your computer, open the ADB binary:  
  • Open command prompt
  • Type: cd path_to_adb
  • Type: adb devices 
• You will see that the system is starting the ADB daemon. If you will see a prompt on your phone asking Allow USB debugging then press OK.
• Enter the following command: adb shell

Example:

 

Remove apps:

In adb shell mode, execute this command:

where name_of_package is the name found in App Inspector, under Package Name. Press Enter and this will uninstall that application.

Example 1 – email app:

Example 2 – Mi Video

To exit shell, type exit and enter.

To close adb:

Source: Miui Forum