Retrieve and Delete Related Entities using Entity Framework

       
        NorthwindEntities ctx = new NorthwindEntities();

	// Retrieves USERS 

	var entity = ctx.USERS().ToList();

	// Retrieve data including its related entities
 	public IList<E> Retrieve()
        {
            var data = entity;
            foreach (var relatedEntity in (((IEntityWithRelationships)data.FirstOrDefault()).
            RelationshipManager.GetAllRelatedEnds()))
            {
                entity.Include(relatedEntity.TargetRoleName).ToList();
            }
            return entity.ToList(); 
        }

	// Retrieves specific USER 

	var _users = ctx.USERS().Where(x=>x.USER_ID == 1).FirstOrDefault();

	// Delete the entity

	public void Delete(bool ClearNavProperties)
        {
            _ctx.DeleteObject(_users);
            DeleteRelatedEntries(ClearNavProperties);
        }
  	// Delete each related entities
        void DeleteRelatedEntries(bool ClearNavProperties)

        {
            if (ClearNavProperties == true)
            {
                foreach (var relatedEntity in (((IEntityWithRelationships)entity).
            RelationshipManager.GetAllRelatedEnds().SelectMany(re =>
            re.CreateSourceQuery().OfType<EntityObject>()).Distinct()).ToArray())
                {
                    ctx.DeleteObject(relatedEntity);
                }

	    }
           
        }	

Note : You can also edit the edmx and add scripts for automatic retrieval and delete 
of the related entities.