I’ve seen this question asked several years ago and some of the referenced links are not found. I recently setup a dedicated server with the interworx control panel. I’ve used plesk and cpanel before and it’s very simple to change a subdomain’s root. My specific need is for a laravel project which needs to be installed on a subdomain as sub.domain.com and not sub.domain.com/public. In other words, I need to make the public directory be used as the root of the subdomain.
For InterWorx 7, the best option is to create the subdomain as a secondary domain. This would allow you full control over the docroot using these instructions: How To: Customize the Apache DocumentRoot — InterWorx documentation
We are working on a feature to allow subdomain docroot modification for InterWorx 8, but at the moment, there is no ETA for that release.
Hope that helps!