Formal:
* Completed
* Concluded
* Accomplished
* Finished (this is a more straightforward option)
* Brought to a close
* Terminated
* Achieved
Informal:
* Done
* Over
* Wrapped up
* All done
* Finished up
* Out of the way
Figurative:
* Put to bed
* Seen to its conclusion
* Reached its end
The best phrase to use will depend on the specific situation and the desired tone.