Which is the most effective way to discontinue service to an intoxicated guest?

The most effective way to discontinue service to an intoxicated guest is to approach them calmly and respectfully, ensuring their safety and that of others. Politely explain that you can no longer serve them alcohol due to their current state. Offer assistance, such as calling a taxi or a sober friend to help them get home safely. Maintain a friendly demeanor to de-escalate any potential conflict.