I used to have an alarm that went off at 6:15am, M-F abd it's been deleted but the Alam is still going off on my S10. The only way to turn it off is to restart the phone. I've tried to clear the cache and reset the alarm and delete but this hasn't helped.
are you using the stock clock app? or other 3rd party alarm app? have you tried it in safe mode if it alarms there or not?
or you can submit an error report via samsung members app (members app > + button > error report)