- Keep it simple and stick to the facts = "This is happening. This is your severance. Sorry."
- Don't plan it and keep it a secret for months - once it needs to be done, just get it done. Otherwise people will be even more pissed at how hard they worked for you when you had no intention of keeping them around.
- Offer severance. In the the USA include continued health coverage for a few months afterwards.
- People are going to be pissed at you. Accept that with grace.
- Do not give empty platitudes of "I take responsibility...." Because you still have a job and a paycheck and probably will get kudos and bonuses for saving the company money.
- If you try to pull the "We're letting you go, but stick around for 6 months to train your replacements", you need to pay massive retention bonuses for that.
Most of all, recognize that you are screwing with your people. Badly. You are hurting them, it is your fault. You are probably going to severely damage some families with really bad timing. So don't spend time saying "how great it was to work with us, how it is not personal, love to work together again...". They do not want to hear that. Just do it and let everyone react and adapt to do what is now needed for their own lives. And please recognize that most of your people now really dislike you - and probably will for a long time. Your bridges are burned, so go away.
As for "leaders be(ing) made accountable", they're already being held accountable by the owners of the business.
Like anything else that needs cleaning.