The pipe character is when you want to list the packages that are installed. When you refer to a specific package for install or removal you precede the package name with a forward slash.
Hafve a look at this article which explains a bit more about how to remove all teh bloatware. It sort of explains DISM better than I can.
https://www.makeuseof.com/tag/easily-remove-bloatware-windows-10/
certainly something strange going on with my windows 10 install..
Add-AppxPackage : Deployment failed with HRESULT: 0x80073CF6, Package could not be registered.
error 0x80070002: Windows cannot create the AppContainer profile for the
Microsoft.Office.OneNote_16001.12624.20042.0_x64__8wekyb3d8bbwe package.
NOTE: For additional information, look for [ActivityId] 4d03c01e-ffea-0003-c458-044deaffd501 in the Event Log or use
the command line Get-AppPackageLog -ActivityID 4d03c01e-ffea-0003-c458-044deaffd501
At line:1 char:37
+ ... s| Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.I ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : WriteError: (C:\Program File...ppXManifest.xml:String) [Add-AppxPackage], IOException
+ FullyQualifiedErrorId : DeploymentError,Microsoft.Windows.Appx.PackageManager.Commands.AddAppxPackageCommand