Drinking a small amount of alcohol occasionally when you are training at a recreational level is fine provided you choose your timing wisely.
Drinking alcohol immediately after training is not wise. At this time you are likely to be dehydrated, and alcohol will dehydrate you more. It's also a good idea to avoid alcohol for a few days leading up to a heavy training session or event.
The amount of alcohol tolerated varies from person to person. Some people can train to their maximum the morning after a couple of drinks, while some can't function.
It's also important to remember that although it's easy to feel relaxed after a few drinks, alcohol is a depressant and too much not only harms your body but can leave you feeling low.
If you enjoy the occasional glass of wine or beer and it doesn't interfere with your performance, there's no reason to give it up.
Keep well hydrated before you have any alcohol and learn to know your limits.