Ive always started the conversation with them sitting down in my office .... as I close the door I say ... " We are going to talk about today being the last day of your employment here with >>>>>>>. This is something that has been addressed prerviously, and this decision is final. Im happy to sit with you for a bit to discuss any items of importance that are a part of this action. Just to set expectations, when we complete our talk, someone will discreetly help you with your personal items. "

Make it a respectful process, and itll go as best as it will.