I'm not quite sure how you came to that conclusion.
Please begin by reading this page: Changing The Site URL, perhaps starting this time specifically below where it says:
In the body of that text, you will find four different methods for changing your site URL's.
1) Edit wp-config.php
2) Edit functions.php
3) Relocate method
4) Changing the URL directly in the database
As far as I can recall, I don't believe any of those methods will require accessing any pages in your dashboard/administration area during the process.