After one hour of research i found a solution on how to delete a computer object in sccm from a remote computer via Powershell. First of all you need to get the computer object from your sccm namespace “ROOT\SMS\site_[yoursite] -> SMS_R_SYSTEM.

All machine items are stored in SMS_R_SYSTEM, so i used a wmi query with a filter to get the object i need.

There are several ways you can get the computer object, another example is a WMI query, that returns the object.

1
2

// Powershell
$compObject = get-wmiobject -query "select * from SMS_R_SYSTEM WHERE Name='[computername]'" -computername [sccm-server] -namespace "ROOT\SMS\site_[yoursite]"

You should check if the $compObject is empty or not and if not you can just use psbase to delete the object from the sccm server completly (not only from the collection) by using this statement

1
2

// Powershell
$compObject.psbase.delete()

How to deal with multiple objects [edit]

Special thanks to Leeni, who wrote a comment at this post on how to deal with multiple entries at your SCCM server. If your WMI query returns more than one object you have to handle this a bit different.

To check if your query returned more than one object try this:

1

$compObject.psbase.length

or

1

$compObject.psbase.syncroot

Both properties are only set if your result contains more than one object, so you can easily check if these objects are empty or not.

If they are not empty you have to delete your $compObject this way

1

$compObject.psbase.syncroot | % { $_.psbase.delete() }

This pipes your syncroot object to a foreach loop (% is an alias for foreach) and delete every object one after another.