To close a job once its done.
Go to the job's page by clicking the job id on your schedule or any of your lists and simply change the job status to "Done".
This will indicate that it is no longer on your to do list.
Note: if your job has a balance, you'll still be able see on your dashboard, clients and invoices that there is a payment due for this job.
Using the mobile app
Open any job by tapping it.
Next tap the status bar and select the done status.
Canceling a job
Alternatively you can always move a job to the "Canceled" status, indicating that this job was not done.
This will also remove it from your schedule and lists.