Take my leave

[Xinfu]

Situation:

At the end of class, if a student wants to know whether he can leave, what are the expressions he can use? Is this OK?

- Can I take my leave?

[Villa]

Situation:

At the end of class, if a student wants to know whether he can leave, what are the expressions he can use? Is this OK?

- Can I take my leave?

It's a very polite or formal way to say goodbye.
Sorry, but I have to leave now.
May I be excused? I have to be somewhere soon.
Have an appointment/meeting to go to.
I have to take my mother somewhere. Airport/doctor/dentist...