I personally recommend you try Revo Uninstaller PRO. It will launch the default Comodo Uninstaller and begin the removal process. After that is complete (or if that fails) you then choose safe, moderate or advanced and Revo Uninstaller PRO will scan for anything relating to Comodo and present you with a list of related Comodo files and registry entries that are usually 99% safe to remove. Personally, I choose advanced. I have never encountered an issue with using Revo Uninstaller PRO and usually forcefully remove all traces of Comodo if performing a clean reinstall. There is a 30-day trial of the Pro version which you will need to use to be able to benefit from the force uninstall option.