I think you can change it if you go to your settings.  I'll show you how I didd it (I'm using a laptop with Chrome; it may look different with different devices)

Go to "Settings" (for me, I go to the upper right and click on my nickname, then click on "Settings"):

This should bring up a new window:

Scroll down to Roles:

Click on the checkmark next to Teacher to turn it off, then click on the blue "Save changes" button:

I hope this works for you!
~ Janice