Newly created alarm clocks are automatically activated on the Samsung device, and can be turned on or off using the clock app or the alarm clock widget.

Alternatively, an alarm clock widget can be added on the home screen, which allows us to directly turn an alarm clock on or off.

Android 10 (One UI 2.0)
Step 1:  Open the  Clock -App
Step 2:  Turn on/off desired  Alarm
  1. Open the Clock-App
  2. Turn on/off desired Alarm

Samsung Instructions