Over the years, I have had to fire a couple of people. The first one was when I was in my early 20's. She was my best friend. She kept showing up to work late, and I told her it couldn't happen again. When it did, I told her I had to let her go. It was interfering with the operation of the place, and putting more work on others. She understood, and went home.
Yes, we are still friends.
I've even had to fire my son. He wasn't doing the job, so I let him go. I did give him another chance (a few more actually), but he was only 13, and I was trying to also teach him an important life's lesson.
It is not always an easy thing to do, but at times it is necessary.