You should use services.msc(Administrative Tools -> Services) to disable cmdagent.exe, and then reboot.
To be able to terminate
ANY process, use
IceSword. It'll install a driver (CFP 3 should warn you about it, just allow it). It'll even be able to kill cfp.exe and cmdagent.exe (since nothing can protect from termination by a driver).
When you've had enough of Oblivion/Stalker, set it to Automatic and then reboot again to get the protection back

Anyways, cmdagent.exe doesn't require too much RAM, so you shouldn't notice any different.
Cheers,
Ragwing