How to change to the complete theme of your website

Hello

First of all congratulations for this amazing template.

I have the theme of www.remarpro.com and I would like to download the original hueman theme in your website https://alxmedia.se/themes/hueman/ with the social share and other improves included, but I am new on wordpress and I am not sure how to do.

Uninstall the them first and download after?
Install it without uninstall the old one?
Will I lose the old configuration?

Thanks in advance