As of now, If a task has been published, it can not be deleted. However, you can hide it from the end users’ visibility by Suspending it. In order to Suspend a task, Please go through the below steps
Bots Admin Console → Bots Management → Enterprise / Consumer Bots → Search for your bot → click on ellipsis symbol on the right corner of the bot(…) → Manage Bot Tasks → Bot Tasks ->There you shall find an option to deselect the task. Once you have deselected and Saved it, the task status would be moved to Suspended and it will not be visible to the end users.
Please go through the below document for more information,