try this code..,may be it helps you.
buttonStop.setOnClickListener(new Button.OnClickListener(){
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent myIntent = new Intent(getBaseContext(),
MyScheduledReceiver.class);
PendingIntent pendingIntent
= PendingIntent.getBroadcast(getBaseContext(),
0, myIntent, 0);
AlarmManager alarmManager
= (AlarmManager)getSystemService(ALARM_SERVICE);
alarmManager.cancel(pendingIntent);
Intent intent = new Intent();
intent.setClass(MyScheduledActivity.this,
AndroidScheduledActivity.class);
startActivity(intent);
finish();
}});
here you can use pending intent for stopping alarm.