I'm sorry I had to end their career.
Who's career did you end?
I was forced to fire a friend because they were annoying all the time.
That's why you ended their career? I am sorry that you were upset with their annoyance, but you shouldn't have interfered in their career. There are many things that your friend could have done to fix it. Maybe they could have worked elsewhere or you could have moved them into another department.
Their karma just wasn't in their favor. They'll find another job eventually.
Nevertheless, if you make a habit of firing good people for insignificant reasons, you'll degrade your workforce over time. The good employees will get snapped up by your competition and you'll go belly up before you know it and wonder what happened. Treat your employees professionally and you will find their work to be of satisfaction.