You are the monitor of your class. Your friend is asking for permission to go out of the class. Have a conversation.

Friend: Hey, can I go out of the class for a minute? I need to use the restroom.
Monitor: Sure. Just be quick and come back as soon as you're done.
Friend: Thanks, I'll be back in a few minutes.
Monitor: No problem. Just make sure you're back before the end of the class.
Friend: Okay, I will. Thanks again.