If you're in the situation of having a single hosting account which allows you to have multiple sites / multiple domains pointed to this single hosting account, and you're trying to move your existing ohsclub.com site into its own subfolder so that in the near future you can create additional sites which will also be "confined" to their own separate subfolders, I think the feature you're looking for is
in your HostGator account as "Sub-Domains".
It's not something that phpBB controls, but every web server instance HostGator is providing has a VirtualHost directive to associate a given DNS name to a specific DocumentRoot directory. Currently your ohsclub.com domain name is associated to what you see as your root directory. And the change it appears you're intending to make is that you wish that HostGator treated the ohsclub.com domain name to have a DocumentRoot of /root/ohsclub.com/ instead. Such that then you can setup other sites with their own DNS name to direct to /root/site2.ohsclub.com/, /root/otherdomain.com/, etc.
It might be safest to just talk to HostGator support about your goal here, in case they know of additional things or configurations you need to consider in order to achieve the result you want. Someone here might happen to have HostGator experience and be able to speak first-hand to what is needed within their specific services, but you can just talk to HostGator support directly and have them look at your specific configuration.
Simply "moving the site to a subdirectory" within a single web server instance is something people do when instead of "phpBB is the only thing my ohsclub.com site has" they are transitioning to "phpBB is just one of multiple things my ohsclub.com site has." And consequently they want their phpBB instance to be accessed by visitors as "ohsclub.com/forum" or similar now, instead of being at the root. That's what you achieved with your current move, making your phpBB site accessible as "ohsclub.com/ohsclub.com", but that doesn't appear to be what you really wanted.