1. Finish the season pass
2. Be on non season server
3. Go to season pass bottom and click graduate.
4. Don't rush and have fun!

Here's a guide that you can use for that

https://www.blackdesertfoundry.com/season-graduation-and-early-graduation/

This guide will walk through step-by-step to graduation including what you need to do before you graduate, getting a free TET-Blackstar and other things.