As a Dev, I want to remove (soft delete) the user from the list of participants of a giving event registration id
Background: Users should be able to leave events, but it would be useful for organizers if it is a soft delete so that: 1) organizers can see total number of people who have left event, 2) organizers can see who left event, so they can maybe see if there are patterns (such as being from certain wikis, communities, etc), and 3) we could potentially have a field/dropdown in the future where participant can optionally share why they are leaving the event that can be shared with organizer. This is not something we need to display in the UI for V0, but it could be useful for MVP and V2.
Acceptance criteria:
The user must be soft deleted on the list of participants in the database