I’ve fired many people in my career. Never felt guilty or bad. It’s because they earned it all by themselves. They were given multiple opportunities to overcome what was causing issue and they either ignored the warnings or didn’t care. Or possibly they were placed in a position above their skill set.
In all cases they earned the termination. No guilt on my part.
I’m thinking if you fired someone and have actual guilt, then very possibly you fired someone who hadn’t earned it. Maybe out of spite or, in some cases, you felt threatened that person could replace you.
Just my opinion.
KC