You can return the favor to the one(s) who offended you, possibly the easiest but sometimes the most efficient way, you can also do something else like talk with friends, do activities that interest you and do not cause you feel anger or disappointment, do anything from listening music and watching a movie to playing a video game, it's probably the best solution in most of the cases. I also don't think it's good to hold anger at all times but in some cases I recommend you to hold it since there are too many things to get angry about and quite a lot of them aren't that significant like Sabb's terrible avatar or random insults thrown by people. Things like that happen all the time so you just have to learn to ignore them. Also deep breaths help too.