localhost still accessing my uploaded website

I’m fairly new to WordPress,though I got my website up and running just fine. Recently the theme was updated and I need to redo some things and would like to use MAMP to work on it on my local drive, just as I did to create the site. So I copied the updated theme to my htdocs folder. But whenever I went to localhost/wp-admin, it would redirect to my uploaded website. I followed the “edit functions-php” method to change the site url as stated in the WP codex. Now the localhost/wp-admin STILL takes me to my uploaded website, even though the URL bar say “localhost/wp-admin”

I’m totally confused. How can I access my site locally? Thanks very much for any help.