If, for some reason, you'd like to quit using The Scheduler add-on, there are two ways for you to do that:
It is important to understand the difference between these two approaches. When you disable the add-on, you will no longer see The Scheduler in your JIRA, and all your Scheduled Issues will be paused, but they will not be deleted. This is the recommended approach if you consider coming back to using The Scheduler in the future and you want to keep your Scheduled Issues - when you re-enable the add-on, all your Scheduled Issues will be resumed again.
If, however, you'd like to remove The Scheduler add-on and remove all your data, then simply uninstall the add-on using the "Manage add-ons" administration section. Keep in mind that all your Scheduled Issues (and any other data, i.e.execution history) will be removed permanently.
Last, but not least, regardless of which option you chose, please send us some feedback so that we could improve.