Open Snapchat and go to the Stories section
Find the Story that includes the Snap you want to remove
Tap and hold the Snap you want to delete
Select Delete or Delete Snap
Confirm by tapping Delete when prompted
If you posted it to a Story and don’t see Delete on the Snap, open the Story you posted and delete the Snap from there (tap and hold the Snap, then Delete)
If it was added to multiple Stories, delete it from each Story where it appears