Incorrectly changed WordPress URLs

I have been developing a new WordPress site over the last few weeks to replace our existing website (https://www.23rdbromleyscouts.org/), and set up a WordPress site at https://www.23rdbromleyscouts.org/wordpress.

This evening I tried to change from the old site to the new site, by changing the two URLs [WordPress Address (URL)and Site Address (URL)] in the Settings > General to remove /wordpress. I hoped migrating the site would be as simple as that, I was very wrong.

I have put hold to the migrating of the site until I properly research how to do it, but I am looking to get back to having the https://www.23rdbromleyscouts.org/wordpress site live, but I am unable to log into the admin area at https://www.23rdbromleyscouts.org/wordpress/admin like I used to do.

How can I change the WordPress and Site URL back to how it was without going into the admin area?

Many thanks for any advice/help!