Use a GPO. It’s the simplest and most efficient solution.

If you insist on continuing down the PS route then below might work but I can’t guarantee it :

$computerList = "" #List of the computers that you wish to target with the script
$creds = Get-Credential domain\user #make sure that this is an Administrator account
$packages = ""
$scriptBlock = "ForEach ($item in $packages) { 
                Get-AppxPackage -Name $item -AllUsers | Remove-AppxPackage
                Get-AppXProvisionedPackage -Online | where DisplayName -EQ $item | Remove-AppxProvisionedPackage -Online 
                }"

foreach($computer in $computerList){

    #Test to see if the computer will accept the connection before continuing
    if(Test-Connection -ComputerName $computer -Quiet){

        #Create a Powershell session on the target machine with the admin credentials from earlier
        $session = New-PSSession -ComputerName $computer -Credential $creds

        #Run the script on the target machine
        Invoke-Command -Session $session -ScriptBlock { 
            Start-Process powershell -verb runas -ArgumentList "-ExecutionPolicy bypass -Command invoke-command -scriptblock {$scriptBlock}"
        }

        #Tidy up the powershell session on the target mechine
        Remove-PSSession $session
    }
}

Built-in apps are called provisioned apps. They are scheduled to be installed for each new user that registers on a Windows 8 PC, so you can't uninstall them completely from the Start screen. To do so, you've to use Windows PowerShell command remove-AppxProvisionedPackage, like so:

remove-AppxProvisionedPackage -package Microsoft.BingTravel_1.2.0.145_x64__8wekyb3d8bbwe -online

That would uninstall the Travel app. To remove Bing Map app, the command would be:

remove-AppxProvisionedPackage -package Microsoft.BingMaps_1.2.0.136_x86__8wekyb3d8bbwe -online

Microsoft.BingMaps_1.2.0.136_x86__8wekyb3d8bbwe is the app package name, which basically is the folder that you find in C:\Program Files\WindowsApps.

To uninstall apps installed from the Windows Store, the command is Remove-AppxPackage. It's syntax is as below:

Remove-AppxPackage PackageFullName

Note: Do not add -online parameter at the end of this command. [source]