This link would show the booking details page, and immediately open a confirmation to cancel this particular occurrence.
Things to keep in mind:
you may click the link after the occurrence finished, so you cannot cancel it anymore. I'd just ignore it in that case and not show anything besides the normal booking details dialog
for a non-recurring booking including this link is not very useful since you can just cancel the booking itself
For the link in the email I'd use .../booking/<id>/cancel/<date>; and then just redirect to the normal booking details modal with another arg (see payload in ModalController) to specify the day that should be cancelled.