COMODO Firewall Help?

when i click on the desktop icon it wont work, it tells me that a file may be missing and aborts the application the same thing happens when i try to uninstall it so i was assuming that it wasnt working. So i went to and got online armor before i switched it on i turned off the windows firewall but it still came up that at least one firewall was switched on on closer inspection it said that comodo firewall was running (i cant access the client though) how can i remove it a completely reinstall it when it wont let me uninstall by clicking uninstall