Hi,
Your question isn't very clear. In particular, when you say "put a project on the schedule," what do you mean. Are you talking about scheduling an Enterprise Guide project? How did you schedule it?
It may vary according to which scheduler is used, but in my experience in general you would need to remove the scheduled job from the scheduler as well. This doesn't happen automatically. If you don't remove the scheduled job, the job may run and fail. Or sometimes the scheduler actually has an independent copy of the job, so it may continue to run.