If you are trying to delete a job or a customer and you get an error that doesn't allow you to delete, it is because that specific job/customer is tied to QuickBooks. You will have give us a call so we can submit a case to our development team. After development 'unties' the job on the backend, you will then be notified and allowed to delete the job.
*****we highly dissuade anyone from deleting anything as some things can NOT be recovered.