How to Delete or retrieve specific workflow ID from a list

Thanks to all for any help!

I am trying to figure out how I delete a specific workflow for a specific user. I currently have a management system for events. When a users says “yes” to attending an event a workflow is scheduled to email them a reminder 24 hours before the event. This workflow is then saved to the event itself. This is great because a user may attend multiple events and need multiple scheduled workflows.

My problem is if a user attends multiple events and decides to no longer attend one event, how do I find their specific Workflow ID from the list of workflow ID’s in the one event they are no longer trying to attend?

Any suggestions on a better way to structure this would be much appreciated.