Go to your People tab (bottom left tab), and from their profile, tap the (...) button at top right. This will display a list of options. Select the option, "Stop Sharing." This will stop that person from being able to access your information on Hio. They will also be removed from your People List.
If you have accepted connection requests on any social media platforms outside of Hio (i.e. Facebook, Instagram, LinkedIn, etc.), you should disconnect with the individual directly from each of those platforms as well.