如何取消此重复警报？

I'm writing something like a reminder for users. Users will set reminders for their events, when the time comes, a repeating alarm will be set to trigger a status bar notification. But the alarm seems non-stop after I selected the notification or cleared the notification. I am not sure where to cancel this repeating alarm. Below are some of the codes: Set up the repeating alarm in my main activityI'm writing something like a reminder for users