Firing people is almost never easy, especially if you are on neutral-to-friendly terms with them. In the case of bartenders, you’re letting go someone who most likely makes a negligible hourly wage and relies on their nightly tips to survive, which makes having to let them go even harder to do.
With a little information, however, firing your bartender can be, if not a pleasant experience, at least a civilized one.
Do not take the coward’s way out and fire a good-natured bartender with a note or phone call unless you’re positive that he will cause a major scene and endanger people or your establishment. Your decision should be based on the reasons you’re letting him go. However, except for very special circumstances, you should always fire people face-to-face. It makes it less arbitrary-feeling to the one being fired, and it allows you to explain and answer any questions he might have.
Sit the bartender down in a secluded area away from the prying eyes of other employees and customers. Explain to her quietly and gently that she is being let go, and list the reason(s) why. Ask if she has any questions, or if possible, offer her a certain amount of employed time to find another job. Remember that this is an embarrassing, stressful moment for your bartender, and you should treat her with respect and empathy.
Leave the fired employee thinking about you as positively as possible, since a disgruntled former employee (especially one with a bartender’s social skills) could cause some serious damage to a restaurant’s local image and clientele.