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:
"There are four easy methods to change the Site URL manually. Any of these methods will work and perform much the same function."
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.