To delete a segment, click on in the row next to a segment and choose the relevant option from the menu. To cancel the deletion process, click Restore.
If a segment is being used as a basis to create other segments, it cannot be deleted until you delete all created segments that are based on this one.
If a deleted segment was being used in your Yandex.Direct or Yandex.Display ad campaign, then such campaigns that included this segment will no longer function correctly. Make sure you change your ad campaign settings in Yandex.Direct or Yandex.Display appropriately by replacing deleted segments with new ones.