If a project has been completed, cancelled, or has been deferred, you'll want to change its status; Marking a project as Completed, Deferred, Cancelled, or Archived prevents further entry of time against the project.
Archived status not only prevents time entry, but it also blocks the project from displaying in the All or My Projects lists on the Project Management > Projects page, therefore you’d typically archive any projects you don’t need ready access to. You might, for example, decide to mark all finished projects as Completed, and then change their status to Archived a year or two later.
You can also mark tasks as complete, which will prevent further entry of time against that task, while allowing its project to remain active.
Refer to How do we change the project’s status? What do the statuses mean? for more information on project statuses.
You can mark projects as Completed, Deferred, Cancelled, or Archived – time and expenses can’t be entered against a project with any of these statuses.
To close a project:
You can close tasks you no longer need to use. Marking a task as closed prevents further entry of time or expenses against it.
To mark a task as closed:
You can only delete projects that have no time recorded against them. Refer to Deleting a project or task for more information.
Refer to How do I find a deleted or archived project? A closed task? for information.
Yes, you can always reopen tasks that have been marked as closed.