I started classcraft last year. I love it. I am using it again this year, so my question is, how do I archive or delete the previous classes so I don't have to scroll through them to get to my current classes?

So glad to hear Classcraft is working for you! :)

You can delete old classes that you don’t need anymore by going to the Classroom Setup screen and then clicking the pencil button next to the class name. The trashcan icon will appear so you can delete the class.