Hello Arna16,
It sounds like you want your Apple Watch alarm only on your Apple Watch. We know how important this is for you, and you’re in the right place for answers.
The first thing to try is the steps listed here. You should be able to disable it in order to resolve your issue:
See the same alarms on both iPhone and Apple Watch
1. Set the alarm on your iPhone.
2. Open the Apple Watch app on your iPhone.
3. Tap My Watch, tap Clock, then turn on Push Alerts from iPhone.
Your Apple Watch alerts you when an alarm goes off so you can snooze or dismiss the alarm. (You aren’t alerted on your iPhone when your Apple Watch alarms go off.)
This info is located in the Apple Watch User Guide: Add an alarm on Apple Watch - Apple Support
Farewell!