Decommission Skype 2015 On-Prem servers

Nicholas Hay​ thanks for the reply, I forgot I posted this here. Would you mind saying where in ADSI you removed the audio test service application?

Anyway, we also raised a ticket with MS Support but as we did not have paid support we first got the reply that they couldn't help us. Unexpectedly, a manager got in touch and basically said we probably could go ahead with running Disable-CSADDomain och Disable-CSADForest anyway, adding:

"I really do think that unless you intention is to remove the remaining stale objects from the skype of business installation, you should go through with running the remaining commands. You should only consider raising the PAID support ticket with Skype for Business team if you encounter error while now running these commands."

So we went ahead anyway, so if you could let me know where in ADSI you removed them I can verify if they remain for us.

We did however run into some other issues with those commands too, which we managed to resolve and I sent back the following to the MS manager in hope it could help someone else so I'll post them here just in case:

1. When running Disable-CsAdDomain, we got the error “Cannot remove the active directory settings for the domain due to ‘FE’ still being activated”. This was due to the Front End server still being AD joined and when checking with ADSIEdit we could see that the AD computer object had some sub objects, my guess is that the command went looking for these. So in order to fix this, we had to remove the AD-object and install the Powershell module and Management tools somewhere else with AD connectivity. After doing this, the step could be run without issue. This site was of help: https://appcentric.com.au/2020/12/09/disable-csadforest-cannot-remove-the-active-directory-settings-for-the-domain-due-to-fe-still-be-activated/3/
2. When above command finished successfully, we ran Disable-CsAdForest and got lots of warnings that the “groups” weren’t ready. This was probably due to AD replication wasn’t finished, so after waiting a little bit we re-ran the command and all warnings were gone except for two, and no matter how long we waited we got the same 2 warnings. After not finding much on this issue we re-ran the command with –Force parameter and this seem to have solved the issue, no more warnings after that.
3. I came across this site which was very helpful, and it sort of explains what things the above commands actually remove: https://expertslab.wordpress.com/2014/04/23/remove-lync-server-from-active-directory/
   1. AD groups, such as CSAdministrator etc, were removed.
   2. AD ACE/Delegations, such as RTCUniversalServerReadOnlyGroup, were removed.
   3. Service Connection Points, such as RTC Services, were removed.
4. Another thing we had to remove manually (besides the FE Machine Account) was the LyncCertificates “folder” (container) in the forest domain; Program Data -> Microsoft -> Distributed KeyMan -> LyncCertificates.