LINK - EF6 Update/Insert/Delete model object from outside of DbContext

Update or Insert:

public void InsertOrUpdate(Blog blog)
{
using (var context = new BloggingContext())
{
context.Entry(blog).State = blog.BlogId == 0 ?
EntityState.Added :
EntityState.Modified;

context.SaveChanges();
}
}

reference - https://msdn.microsoft.com/en-us/data/jj592676.aspx

Delete by PK:

Customer customer = new Customer () { Id = id };

context.Customers.Attach(customer);

context.Customers.Remove(customer);

context.SaveChanges();

reference - http://stackoverflow.com/a/28050510
Partial Update:
public void ChangePassword(int userId, string password)
{
var user = new User() { Id = userId, Password = password };
using (var db = new MyEfContextName())
{
db.Users.Attach(user);
db.Entry(user).Property(x => x.Password).IsModified = true;
db.SaveChanges();
}
}
reference - http://stackoverflow.com/a/5567616