You don't have to do that. 你不必这么做。
1. If you are unwilling to tell them, you don't have to do it.
2. You don't have to come so early.
3. You don't have to wait for my permission.
A: Thank you so much for coming tonight. Everybody really enjoyed your performance.
B: I'm glad I could help.
A: Here's the check. I included a little extra for you.
B: You didn't have to do that!
A: I know, but you deserve it.