Can you go back to a previous System Restore point?
--- Maybe you can get back to a time before the inability to uninstall KB2952664
It appears to me you are already doing this but for verification purposes:
Set Windows Update to: Check for updates but let me choose whether to download and install them
Check for KB3035583, KB3068708, KB2952664, KB2990214, KB3021917 & KB3050265
(As you mention, KB2952664 doesn't want to take no for an answer in addition to being reported as an important update etc. I have seen that issue also)
--- Uninstall any of them that are installed.
--- Some will require you to shut down upon uninstalling, some won’t
--- If some don’t uninstall at this time, do which ones you can
--- Myself I shut down and start back up for each one anyway.
--- Either way shut down: start back up when completed.
--- Go into Windows Update and watch for which ones return in both Important and Optional updates and hide them
--- It doesn’t take long for any of them to return at first; eventually maybe a couple of days in some cases
You might have to repeat the above procedures for a few days
I cannot say that all of the following procedures will work for you but check them out
Kill "Get Windows 10 (GWX)" Process Using Task Manager.
--- Right-click on Taskbar and select Task Manager option. It'll open Task Manager.
------ You can also directly launch Task Manager by pressing Ctrl+Shift+Esc keys together.
--- Go to Processes or Details tab and select GWX process and then click on "End Process" button.
------ You can also right-click on GWX process and select "End Process" or "End Task" option.
------ Or you can simply select GWX process and press Delete key.
------ It'll kill GWX process and will also remove its icon from Taskbar notification area.
Delete "Get Windows 10" Task from Task Scheduler.
Run taskschd.msc. Go to Task Scheduler Library -> Microsoft -> Windows -> Setup.
Under Setup key, you'll see 2 more sub-keys: gwx & GWXTriggers.
Disable all tasks present under "gwx" key; launchtrayprocess & refreshgwxconfig
If you have a 32-bit system
There’s also a 32-bit registry hack that you can use to prevent the icon from showing up.
--- Browse down to the following key, creating it if it doesn’t exist:
--- Once you are there, create a new 32-bit DWORD value on the right-hand side named DisableGWX, and give it a value of 1.