Apparently Microsoft has (sort of) replaced the \"Favorites\" Windows explorer item with the Quick Access item. But I haven\'t been able to find a way to programmatically ad
Yohan Ney's answer for pinning an item is correct. To unpin an item you can do this:
$QuickAccess = New-Object -ComObject shell.application
($QuickAccess.Namespace("shell:::{679f85cb-0220-4080-b29b-5540cc05aab6}").Items() | where {$_.Path -eq "C:\Temp"}).InvokeVerb("unpinfromhome")
Here's a script I wrote to make pin/unpin a little easier:
https://gallery.technet.microsoft.com/Set-QuickAccess-117e9a89