Unregistration of Event

[suffisme]

Following the issue #1 if someone wants to unregister from the event.

The function should allow users to unregister from event.

The request body contains unqiue ID of event and user only.

• user model should have events_enrolled field which previously contained the event ID in it. Remove that ID from the array
• events model should have user_enrolled field which is array of object containing data regarding user, remove that too from the list.

NOTE:

• After unregistering the event, the user will have no record / history regarding the event.
• User can register again in the event.

Additionals:
Think about how history can be maintained while allowing the user to register again in the same event.