All we have to do is to search “wp-admin” in all wordpress files and change it to what we need to use as a admin directory name. Let’s name it for example “profile”. There are over 50 files to change. It’s practically impossible to find all these files manually so we need this great software called “grepWin” (Download). After installing this software right click on your wordpress folder and then choose “grepWin…” (see image below)
Then type “wp-admin” in “Search for:” box and “profile” (or anything you wish) in “Replace with:” and click “Replace”. This software will find every “wp-admin” and replace it with “profile”.
Now we are almost done. There is one file in /wp-admin/ directory called wp-admin.css. You have to change it’s name to “profile.css” (your_admin_directory_name.css).
Please note that some plugins and themes may also use the “wp-admin” name somewhere, so before you upload any theme or plugin don’t forget to scan it using grepWin and change every “wp-admin” to your chosen directory name.