You want to modify an event category. Find out how to do it in this article.
If you don't know how to create an event category, please read our article How to create an event category?
In your organization dashboard, go to " MANAGE ", then click on " Event categories ".
For the event category you want to modify, click on the small blue pen at the end of the line.
Modify the field(s) you want to change and click on " Save ".