If you want to delete a Snapchat message, just press and hold it, hit Delete, and confirm. Just so you know, the other person will see “This message was deleted” if they check, and anything they’ve saved or already opened can’t be removed.
Press and hold the sent message and choose Delete — this removes it from both chats if the recipient hasn’t saved it or taken a screenshot.
If the message was saved the other person must Unsave in Chat (or you’ll need to ask them); deletions don’t guarantee removal of copies or screenshots.