While you cannot delete only some future instances of a Recurrence Template at once, you can delete either one or all future instances, then recreate instances as desired. The steps below describe how to delete all instances of a Recurrence Template. (If you are only trying to delete an individual instance, you can do so by navigating to that instance, clicking the ellipsis (...) button to the right of the instance and selecting "Delete Event" from the menu that appears.)
For a full guide on how to use recurrence templates, please refer to the Quick Guide to Recurrence Templates.
Navigate to Recurrence Templates page from the main menu.
Click the ellipsis (...) button to the right of the template you'd like to delete and select "Delete Template" from the menu that appears.
You will have the option of auto-notifying registered users of the event on another prompt. After you make your choice, the template will be deleted.
This will delete all future instances of the existing template. If you would like to continue using the template, simply use the filter option on the Recurrence Templates page to show deleted events only, then click the ellipsis (...) button beside the deleted template you want to reuse and select "Undelete Template" from the menu that appears.