How do I delete a segment?
On the page Subscribers → Segment, you can find an overview of all segments you have made for a specific list. You get to this page by selecting the relevant list on the Subscribers page, for instance by clicking 'View'.
To delete a segment, you click Edit in the overview table. You will be directed to a new page, where you can change the name and definition of the segment. You can delete the segment at the bottom of the page.