Teacher account getting added to other teacher classes

I'm a 4th grade teacher, and I keep getting added to other teachers' classes. How do I remove myself? I know this is happening because we use Google Classroom to set up our Khan accounts, and any classes we're co-teaching in GC show up as teacher classes in Khan. I don't see a way to remove myself, and in some cases, I'm in a teacher's class who retired and no longer has access to district accounts. 

Thank you!