I think you’ll find that most uninstallers tend to leave remnants behind after they have been uninstalled. CCleaner is a very good application in terms of it being able to clear out rather a lot of unwanted junk in your registry.
I very often have to go to the “my programs” folder and remove old folders and config files that uninstallers leave behind, its a common thing not specific to Comodo, and I’m willing to bet there is a reason for it. No company would purposefully make software that doesn’t remove itself properly unless there were technical restrictions.
for anyone trying to uninstall firewall with D active simply deactivate the defense reboot then uninstall firewall ,had a problem one time with Online Armor won’t let me uninstall then after deactivating the HIPS I uninstalled it with no problems, maybe it will work the same way with Comodo.hope this helps.