Within Teamwork Projects, you can mark any of your projects as complete in the project's settings.
Go to the Overview tab of the project you want to complete:
Click the options (three dots) in the top right of the section, and choose Complete Project from the Manage Project tab:
If the project has been assigned start and end dates, you can also complete the project by clicking one of the dates in the pane on the left side of the 'Overview' section. You can also click the edit pencil:
In the start and end dates modal, you will see an option at the bottom, to mark the project as complete. Click 'Set Project Dates' to save the changes:
Note: Once all tasks and milestones in a project are completed, you will still need to mark the project itself as complete.
For more information, see: Completed projects