How do I stop Time.Alarm in my sketch?

I am not clear what you want to do exactly, and your current code does nothing as far as I can see, apart from constantly setting the time to the same values every time through loop(). The alarms will not trigger because you have no call to Alarm.delay() in loop() and even your Resetingeverithing() function does nothing but wait 2 seconds, clear the LCD and then print a message.

If you want to turn alarms on and off you need to know their ID, which you get like this

ID = Alarm.timerOnce(60, spinning);

Then, to disable/enable an alarm do this

  disable(ID);  //-  prevent the alarm associated with the given ID from triggering   
  enable(ID); // -  enable the alarm