Login Secure

Login Secure is an easy to use and user-friendly WordPress plugin that secures your website from unauthorized users. Blocks default WordPress login URLs and requires a special code in WordPress Login URL.

After installing and activating the plugin, go to ‘Settings>>Login Secure’ link. Enter a unique string and click save changes.
Your WordPress login URL will be the one displayed on that page.

After storing unique string, your defualt WordPress login URL will not work, even user can not login by going to
http://example.com/wp-admin where example.com is your WordPress installation link.

Download & Installation: https://wordpress.org/plugins/login-secure/