Here are my solutions updated to work with AdventureWorks on 2008R2.
1. Write a DELETE query that would remove a record from person.contact by contactID, pick a contactID that does not exist in person.contact.
DELETE FROM Person.Contact WHERE ContactID = -1
2. Write a DELETE query that would remove a record from person.contact by first and last name.
DELETE FROM Person.Contact WHERE FirstName = 'JarJar' AND LastName = 'Binks' --Please, oh please delete him!
3. Write a DELETE query that would remove a record from example.person where they also exist in person.contact.
DELETE FROM ep FROM Example.Person ep INNER JOIN Person.Contact pc ON ep.FirstName = pc.FirstName AND ep.LastName = pc.LastName WHERE pc.FirstName = 'JarJar' AND pc.LastName = 'Binks' --We have to make sure he's gone!
If you have any problems with these solutions, please let me know. I want to make sure we’re on the same page.