I'm off duty.

我下班了。

《柯林斯英汉双解大词典》

youdao

When do you come off duty?; What time do you knock off?

你什么时候下班?

《新英汉大辞典》

The device was spotted by a police officer coming off duty at New Barnsley.

BBC: Northern Ireland

Now that Klum is off duty, her hair is no longer blown out and looks darker.

FORBES: Heidi Klum Reboots: The World's Most Famous Model Makes Over Her Life

Most of the policemen were ambushed when they were off duty, often when arriving at their homes.

BBC: Sao Paulo police at war with prison gang