Get an email the day before to deactivates someone’s access at X time. Next day they get called into a meeting 10 mins before X and then escorted to their desk and out a couple mins after.
What really sucks is when you have to do it for one of your teammates. :-(
I don't know the full details, I think she did have some kind of warning weeks before, but ignored it because she thought she was immune to being fired. She was the worst developer I've ever worked with so far though, personality-wise and skills, she definitely lied in her PHP interview. That's also on that company though, I have no idea how she passed that interview (okay, I do have an idea, no programmers ever spoke with her).
It's not only in the movies. I've seen it done in real life a number of times. In the US, anyway, this isn't prohibited by law.