You can remove any passage in the flow except the Starting Passage. Make sure you edit any incoming passages or questions first, to avoid disrupting the flow of your chatbot.
Create a backup version...
Deleting a passage can't be undone. If you want a backup of this passage, create a version of the chatbot before you delete the passage. See Versions.
To delete a passage, click the menu icon in the top right of the passage, and click Remove.