Formal:
* Completed: This is a very common and straightforward way to say something is finished.
* Finished: This is another simple and widely used word.
* Concluded: Implies a formal ending to something.
* Accomplished: Suggests the task was successfully finished.
* Fulfilled: Indicates that something has been done as required.
* Achieved: Similar to "accomplished" but often implies a goal was reached.
Informal:
* Done: This is the most casual way to say it.
* Finished: Slightly more formal than "done."
* All set: Means ready to go, everything is done.
* Through: Often used for tasks or activities.
* Over and done with: Means the task is finished and won't be repeated.
* Wrapped up: Suggests a completion of something that might have been complex.
* In the bag: Means something is guaranteed to be done.
Phrases:
* That's all, folks!
* I'm done for the day.
* We're good to go.
* We're finished here.
* That's a wrap!
The best word or phrase to use will depend on the specific situation and the tone you want to convey.