Most Helpful Girl
No different from a regular relationship.
-Delete photos and videos.
-Delete their email.
-Block their contacts and delete their contacts.
-If mutual friends and family knows, remind them that your not involved with that person no more, and you don't want their name brought up in front of you. Don't mention them, don't tag you with them.
-And also apply this to yourself as well. Don't mention them, try not to think about them.