Deleting an association over REST in Spring Data REST+HATEOAS

I wish to know how to delete a many-to-many association via a REST call. I am able to create records, and associated them, but do not understand how to delete.

I have a Spring Boot project where i'm using REST and HATEOAS to by pass Services and Controllers and expose my Repository directly.

I have a User Model/Domain class

@Entity
@Table(name = "usr")
public class User implements Serializable {

private static final long serialVersionUID = 1L;

@Version
private long version = 0;

@Id
@GeneratedValue(generator="optimized-sequence")
private Long id;

@Column(nullable = false, unique = true, length = 500)
@Size(max = 500)
private String userName;

@Column(nullable = false, length = 500)
@Size(max = 500)
private String firstName;

@Column(nullable = false, length = 500)
@Size(max = 500)
private String lastName;

@ManyToMany(    fetch = FetchType.LAZY, cascade = CascadeType.ALL)
@JoinTable( name="user_role",
            joinColumns={ @JoinColumn(  name = "user_id", 
                                        nullable = false
                                    ) 
                        }, 
            inverseJoinColumns={ @JoinColumn(   name="role_id", 
                                                nullable=false
                                            ) 
                                }
)
private Set<Role> roles = new HashSet<Role>(0);

...Getters/Setters Below...

As as you can see, I have a roles member that is Many-To-Many association with Role class, of which the code is such:

@Entity
public class Role {

@Id
@GeneratedValue(generator="optimized-sequence")
private Long id;

@Column(nullable = false)
private String name;

@Column(nullable = false)
private String description;

...Getters/Setters Below...

My repositories look like so:

UserRepository

public interface UserRepository extends 
        JpaRepository<User, Long>, JpaSpecificationExecutor<User> {

    List<User> findByUserName(String username);

}

RoleRepository

public interface RoleRepository 
        extends JpaRepository<Role, Long> {

}

Now, all is well. When I access the project root from a browser, I get the repository index/directory in JSON+HAL format. Wonderful.

(Note I'm remove the http:// part from the test below because StackOverflow is counting it towards my links quota)

I, using WizTools REST Client, HTTP.POST to the Role ( localhost:8080/resttest/roles ) repository and create a new Role. Success, Role ID #4 created.

Then I POST to the User repository to create a User ( localhost:8080/resttest/users ). Success, User ID #7 created.

Then I PUT to the User repository to create an association with the role:

PUT localhost:8080/resttest/users/7/roles
Content-type: uri-list
Body: localhost:8080/resttest/roles/4

Great! Association made. User 9 is now associated with Role 4.

Now I can't for the life of me figure out how to DELETE this association.

I'm sending an HTTP DELETE instead of PUT with the same command as above.

DELETE localhost:8080/resttest/users/7/roles
Content-type: uri-list
Body: localhost:8080/resttest/roles/4

I get back: HTTP/1.1 405 Method Not Allowed

{
    "timestamp":1424827169981,
    "status":405,
    "error":"Method Not  Allowed",
    "exception": "org.springframework.web.HttpRequestMethodNotSupportedException",
    "message":"Request method 'POST' not supported"
}