A job may be deleted once it has been set inactive - either progress the job to an inactive status, or edit the job and choose status "inactive".
Note that an admin user can delete a job at any time - regardless of the current status.
If you have de-activated a job, it will be hidden from search results - so use the "Show inactive" button on the job list screen to find your inactive job.

Once you are viewing an inactive job, click "Delete".

Before being permanently removed, you are asked to review the items attached to the job, such as the components, invoices and tasks.
If you still wish to proceed, click "Confirm permanent removal" from the taskbar. This operation cannot be undone.