How To Completely Uninstall All Built-in Windows 8 Apps ?
Step 1:
Open elevated PowerShell. To do this, first switch to the Start screen, start typing PowerShell and then press Ctrl + Shift + Enter hotkey to open Windows PowerShell as administrator.
Step 2:
In the elevated PowerShell, type the following command to completely remove all native apps from your current user account:
Get-AppxPackage | Remove-AppxPackage
if you would like to uninstall all modern apps from all user accounts (if you have two or more), execute the following command:
Get-AppxPackage -AllUsers | Remove-AppxPackage