Re: Change /wp-admin URL? How to restrict user access to wordpress backend.
You probably already tried this tutorial:
The other technique is hacking WP core files:
You could also try applying a filter to “admin_url”, but when I tried this awhile back, it didn’t work:
I should note that I’ve never done this and strongly advise you not to as well.
WP should have a defined WP_ADMIN_URL variable similar to WP_PLUGIN_URL and WP_CONTENT_URL, but it doesn’t.