Delete a SCCM collection from the command-line - powershell

Question

When using the UI (SCCM 2012), to be able to delete a collection (let's say CollA), you need first to ensure it is not linked by any rule to another (let's say CollB, etc..) such as :
CollB includes CollA
CollC excludes CollA
When dealing with a lot of collections, deleting a collection can be time-consuming. For that reason, I have created a script,
usable remotely to avoid the need to connect through RDP
which checks that CollA has no rule left (even if that is not a problem if we want to delete CollA)
which checks if CollA is "linked" to other collections (include or exclude rules)
which deletes any rule found (between CollB and CollA, between CollC and CollA)
I'm stuck now for I can not find a way to delete CollA.
For authentication matters and for remote purpose, I use a lot Powershell and WMI.
$CollA=Get-WmiObject -computername servername -namespace root\sms\site_111 -credential $cred -query "select * from SMS_Collection where Name='Tartempion'"
$CollA.get()
At that point, I found a method Delete(), which when I try to use it, it gives me :
Exception calling "Delete" with "0" argument(s): "Generic failure "
At line:1 char:1
+ $coll.delete()
+ ~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : DotNetMethodException
If that is the method that I should use, what are the arguments to be passed ?
EDIT 1
As pointed by theMadTechnician, the SCCM collection, once retrieved in $CollA, a System.Management.ManagementObject.
I should, as described in the MSDN pages, be able to use the following method :
Delete() > produces the error mentioned above
Delete(DeleteOptions) > I can not find the specs for the required options
Delete(ManagementOperationObserver) > I can not find the specs for the required options
To ensure I properly understood the MSDN page regarding *.Delete(), i tried (successfully) the following:
PS C:\> Set-WmiInstance -Class win32_environment -argument #{Name="testvar";VariableValue="testvalue";UserName="<SYSTEM>"}
PS C:\> (gwmi -class win32_environment -filter "Name='testvar'").gettype()
PS C:\> (gwmi -class win32_environment -filter "Name='testvar'").delete()
EDIT 2
The fact is that when deleting a SCCM collection through the console, the collection is not the only thing removed from the inventory : the assignments for instance, are too removed. It reminds of the CASCADE switch when dealing with MySQL or ORACLE. Maybe what I'm trying to do is not possible
without using the console
without using the SCCM cmdlets
If it can not be done that way, I just need to be sure.
EDIT 3
After some maturing, I am starting to wonder if it could be a authorization matter. I mean, the account I am using with the "-credential" switch or when connecting to the server, to open a SCCM console, allows me to create/update/delete collection but, for instance, it does not allow me to delete a device. I would expect the error message to be different but who knows ?
More or less about the same matter (sorry for the digression), trying to remove a device from the commandline, I found this and I have the same error message (see above). If it works for others and not me, could it be authorization related ?
EDIT 4
I requested a service account with more "privileges" than I have with my technical account.
I tested and I have the same error. I am putting aside the authorization hypothesis.

Answer 1

I just tested this in our SCCM 2012 environment by using the following command:
$CollA=Get-WmiObject -computername servername -namespace root\sms\site_111 -query "select * from SMS_Collection where Name='Tartempion'"
Basically, take the -credential out of there. Does it work now?

Answer 2

You could potentially setup a script like so:
#if the delete command fails...
if(!($?))
{
$limitedcollectionName = $colla.LimitedCollectionName
$limitedcollection = Get-WmiObject -computername servername -namespace root\sms\site_111 -query "select * from SMS_Collection where Name=`'$limitedcollectionname`'"
$limitedcollectionname.delete()
}