When you archive a job, existing tasks of that job are also archived but not deleted. They are only hidden from general view.

***Note***Only account administrators can archive jobs when there are accounts linked to them.

To archive a job you must click on the icon that looks like a filing tray.

To see archived Jobs, include archives and search again. 

If you are the owner or watcher of a job  and it is archived by another user, you will be notified via email that the job has been archived. You can still retrieve those jobs in the future and view them again.

See the tutorial below: