(Curts, Eric. "6 End-Of-Year Google Classroom Clean-up Tips." Controlaltachieve.com. n.d. Web. 12 Jul. 2017. <http://www.controlaltachieve.com/2017/05/classroom-cleanup.html> )
Tip #1 - Return all student work
So, one of the first tips to consider is to make sure you have properly returned all the Classroom assignments to your students.
One way to do this would be:
Tip #2 - Un-enroll students from old classes
Another possible clean-up step is to remove students from the old classes. This may be an option for you if you prefer not to have students accessing content from your class in the future.
Tip #3 - Archive old classes
When you are done with a class, a good way to clean up Classroom is to archive the old classes. Archiving is a process that:
Tip #4 - Remove old class calendars
A calendar is automatically created in Google Calendar for each class. This is a convenient way for your and your students to go to Google Calendar and see upcoming due dates for classwork and projects throughout the course of the school year.
Tip #5 - Move old class folders in Drive
Because Google Classroom automates the sharing and collaborating process, it is easy to forget what is actually going on behind the scenes in Google Drive. For each class you create in Google Classroom, a folder gets created in your Google Drive where all of the assignment documents and other files are stored.
Tip #6 - Remove old class files from "Shared with me" in Drive
When files get shared as part of a Classroom assignment, sometimes the files will also show up in the "Shared with me" area of your Google Drive. If you have a lots of students and lot of assignments, this can cause quite a mess in "Shared with me".
Tip #6 - Naming Convention
Google Classroom Header Template - Create your own to make your Google Classroom even more unique. Blog with more information here