done meaning “finished”
I’m done for I have finished.
I’m done meaning I have finished is standard in speech and is common in informal use. Prefer I have finished or I’m finished when the register is formal. Done as the past participle of do after a form of have is a different use: I have done the work.
Examples
UseI have finished the brief.
UseI’m done with the brief.
AvoidI’m done the brief. (If you omit with or finished.)