After asking to be remembered to return a call, geofence won't go off When someone called me, I tapped on the "Remind me later" button, I called back without the phone telling me, but I noticed that the geofence icon won't shut off even after resets. Why is this happening and how can I prevent it from draining my battery? According to the Location Settings the service that is using geofence is the location based alerts.
To disable the reminder, open Reminders.app and check the "Call [person]" reminder. 

With location based reminders, they will go off every time you enter (or leave, depending on the setting) the area until you mark them as completed. 



Very much a side note, but in iOS 9 you can now keep tabs on what apps are draining your battery. So if you are concerned about battery drain, go to Settings -> Battery and validate (or invalidate) those concerns.