Trying to hide things is really not the most effective security approach. You can easily hide things from human visitors, but Bots will not be fooled by trying to hide something. What is the best security approach to protect against brute force dictionary cracking attacks on your login page is to limit the number of failed login attempts.
There are several login plugins that allow you to limit the number of failed login attempts to a number of failed login attempts that you pick and will then automatically lock that user account from being able to try and login for an amount of time you specify. Example: 5 failed login attempts locks that user account from being able to attempt to login for 24 hours.
Obscurity is an effective method of security protection and in the case of login pages choosing an obscure Admin login username is how that is best acheived. Be sure to make the displayed Admin name in comments different from your actual Admin login username. ;)