To make sure that your photos and everything are removed from the internet, you first need to delete your account. To delete snapchat just click the following link, and if you have not yet signed in, you will be asked to do so. Sign in and DELETE your account.
DIRECT LINK FOR SNAPCHAT DELETION PAGE: http://www.snapchat.com/a/delete_account
After clicking the above link, you will be asked to confirm your action, then snapchat team will warn you that this could take up to 48 hours.Confirm account deletion by filling all required fields.