delete https://api.onesignal.com/apps//segments/
Delete segments from OneSignal. Does not delete users or subscriptions.
Overview
The Delete segment method is used when you want to programmatically delete a segment from within the OneSignal Dashboard UI.
Once deleted segments can't be restored unless it's recreated
How to use this API
You can pass in the segment_id
dictating which segment from our dashboard will be deleted.
The segment_id
can be found using the View segments API or in the URL of the segment when viewing it in the dashboard as shown below:

Example shows segment ID = 0c18c3f8-d92f-4505-80ec-dd9b971f74bd