Gee, if you shut down your server, that should do it. Computers won't run cron jobs while they're shut off. And yes, the start up scripts should restart cron when you power up your system.

If you want to stop and restart cron while leaving the server up, there is generally a way to that safely by running the cron start-up and shut-down scripts manually. If you tell us what type of system you have, we can help you with details on this.