I found this post which states that you have to wait for the computer to uninstall the client for these to be fully removed from the console: https://forum.avast.com/index.php?topic=199432.0
The problem is this:
What if those machines no longer exist? Will my console continue to be filled with devices in an Uninstalling status? I have dozens of devices in this state already and some of them have been that way for months now. Can the system make the assumption that if it hasn’t seen the system after a specific amount of time that it removes it from the console anyway?
Try to remove them again. The current release of the console seems to do much better in this regard than past versions. I have not seen a client stick after uninstall in quite a while now
I think it is bad idea to have system removed by default after it hasn’t been seen by the console for a while.
It can be the owner is on holiday, in the hospital (I hope not of course), the system is out for repair and such.
Saying that, a alert if is system hasn’t been seen in e.g. 6 months and asking if you want to remove it might be idea.
The console doesn’t remove the client automatically. Dreaken is referring to after you remove a client from the console, the console continues to show the client listed until it checks in to the console to get the uninstall command, however some clients which are lost/reformatted/etc will never check in again and it used to be that they would be forever stuck in the console.
Mac is correct. The systems that are not being removed will never be coming back for them to be uninstalled. Is there a way to forcibly remove a system or no?