Log-in Issues

I recently registered https://www.pmwracing.com through Bluehost and linked it with WordPress. I just today logged into the admin page for WordPress at https://www.pmwracing.com/wpinstall (which is where I had located it), then went to General Settings and changed the ‘WordPress URL’ and ‘Website URL’ from ‘www.pmwracing.com/wpinstall’ to simply ‘www.pmwracing.com’.

Now, when I go to pmwracing.com/wpinstall, a shadow of the former website appears and when I try to click ‘Log In’ under the ‘Meta’ header in the bottom right hand side, it says ‘Error 404 Error File Not Found – The page you are looking for might have been removed, had its name changed, or is temporarily unavailable’. I’m worried I’ve somehow screwed up the admin log-in page and won’t be able to get back to the admin page to edit the website. Does anyone know how to resolve this??