In California, you sometimes have to announce layoffs. This strengthens a class action lawsuit that this is a layoff and not a termination for performance. There will be penalties associated with that.

You can simply say "We are terminating your employment." However, that generally means that you cannot demand back relocation, bonuses, stocks, etc. and you're going to have to cough up equivalent severance to everybody else--otherwise you're staring at a discrimination lawsuit.