I’m making an archive and I wanna use Omeka S. I’ve tried Omeka Classic but so far Omeka S is just a lot more polished and seems to have more options. However, it seems like it’s not possible to have the archive under your domain. It has to be domain.com/archivename and not just domain.com. Isn’t there a way to just have your site under your domain without a directory like on Omeka Classic?
Hi, try the module Clean Url Omeka S - Clean Url 
Go to global Settings and look for Default site.
You can select which site should appear when users go to the front page of the installation – in your case, the one site you will have.