HELP: Redirect error | WordPress.org

I usually do the admin of this website here

In a moment of stupidity I changed the WordPress Address (URL) AND Site Address (URL)
to leticia.tootington.com

I realised it was a stupid idea and tried to change back but now I can’t get access to the page and get the error

This site can’t be reached leticia.tootington.com’s server IP address could not be found.
Try:

Checking the connection
Checking the proxy, firewall and DNS configuration
Running Windows Network Diagnostics
ERR_NAME_NOT_RESOLVED

I’d like it to just go back to how it was i.e. leticiagolubov.tootington.com instead of leticia.tootington.com but I have not found a way changing it as I can’t get to the settings.

The original full website address

The page I need help with: [log in to see the link]