You can delete a task.

If you have already started it, tap on the "Delete" button in the regatta window. Please note that the canceled task will be considered used and will reduce your task limit in the regatta.

If you have not started the task. You can delete an task, which is shown in the general list of tasks, if you have the necessary permissions (you are the Governor, Vice-Governor or Mayor). To delete a task, select the task in the list and tap the "Delete" button.