You can delete and restore jobs, just as you can with Customers and Job Addresses.
When you delete something, it gets moved to the Archived tab. You can search your archived items from the website only, and restore them with a click.
The items that are archived are not included in a normal search - you must have selected the Archived tab and then search.
Select the archived item you want to restore, and click the grey restore button on the bottom left.
You will be prompted with the option to unarchive the job, and all its records will return to their previous state.