You can easily Delete a Template.
Deleting a Template will not create any more Tasks in the future and you can select if you want any existing tasks to be deleted.
Go to the Automation board of the CONNECT Portal.
Select the Template that you want to delete.
The Template Details Tile will open up.
The bin icon on the top right of the Details Tile is the Delete button.
Select which Tasks from this Template you want to delete, then click Delete.
All Tasks including completed - will remove every task ever made from this template.
All Incomplete Tasks - removes all tasks that are on the Work board (but will not remove tasks on the Completed board).
All Tasks that exist in the future - remove all tasks that have a Start Date after today, (not removing tasks that started before today, or Completed tasks).
None, remove only the template and its schedules - won't remove any existing tasks, but also won't make any more tasks in the future.