Good suggestions by other members above.
Also consider
Malwarebytes RegASSASSIN for deleting pesky registry keys.
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My personal suggestion, though, would be to install COMODO again, and then uninstall it normally through its uninstaller.
EDIT: Just read that you resolved the issue.
Do consider
RegASSASSIN for deleting any locked registry key in the future though; I have been using ever since I first started using Malwarebytes Anti-Malware and it works wonderfully.