Can’t access Backend bc ERROR 404 (changed URL in settings)

So i wanted to put the blog on the root level so I read the support forum and it said to go into settings, change the URL location for both to the root folder… so I did. And now I cannot login AT ALL to the backend and change it back.

Is there a way I can access the settings in the files on the FTP or on my local drive to change it back?

So then I tried to reinstall and it keeps telling me it’s already installed… can’t uninstall in any way?

Please help!