I also can`t switch off my alarm, no swipe or side buttons don`t work. I have to unlock phone, go into alarm , switch it off there and then only after closing the alarm app will it stop..VERY ANNOYING. !!!
I would suggest that you first of all try to clear data for clock under settings > apps > all > clock > clear data. Restart your device and try to set a new alarm and see if you are able to snooze/turn it off properly.
